Refit API reference¶

Find Refit types, overloads, parameters, and return values in one place. The tables are grouped by category and topic. Follow a topic link for its walkthrough, examples, and detailed behavior. Use your browser's find command to look up a type or method name.

Clients and settings
Requests
Results
Serialization
Testing
Advanced APIs

Overload	Description	Parameters	Returns
`RestService`	Static factory class for creating Refit interface implementations.	None.	—
`CreateHttpClient(string hostUrl, RefitSettings? settings)`	Creates an HTTP client, chooses the configured handler chain, and sets its base address.	`string` `hostUrl`: non-null, non-whitespace base address; `RefitSettings` `settings`: nullable settings for handlers and URL resolution.	`HttpClient` with the configured base address; the caller owns it.
`ForGenerated<T>(HttpClient client)`	Resolves the registered generated implementation for `T` with default settings and never builds reflected requests.	`HttpClient` `client`: non-null client used by the implementation.	`T`: generated implementation; if `T` inherits `IDisposable`, disposing it also disposes `client`. Throws `InvalidOperationException` when no generated implementation is available on modern .NET.
`ForGenerated<T>(HttpClient client, RefitSettings settings)`	Resolves the registered generated implementation for `T` with the supplied settings and never builds reflected requests.	`HttpClient` `client`: non-null client; `RefitSettings` `settings`: non-null serializer and request settings.	`T`: generated implementation; if `T` inherits `IDisposable`, disposing it also disposes `client`. Throws `InvalidOperationException` when no generated implementation is available on modern .NET.
`ForGenerated<T>(string hostUrl)`	Creates an HTTP client with default settings, then resolves the generated implementation for `T`.	`string` `hostUrl`: non-null, non-whitespace base address for the created client.	`T`: generated implementation; if `T` inherits `IDisposable`, disposing it also disposes the created client.
`ForGenerated<T>(string hostUrl, RefitSettings settings)`	Creates an HTTP client with the supplied settings, then resolves the generated implementation for `T`.	`string` `hostUrl`: non-null, non-whitespace base address; `RefitSettings` `settings`: non-null serializer and request settings.	`T`: generated implementation; if `T` inherits `IDisposable`, disposing it also disposes the created client.
`ForGenerated(Type refitInterfaceType, HttpClient client, RefitSettings settings)`	Resolves a generated implementation for the runtime interface type over the supplied client.	`Type` `refitInterfaceType`: non-null Refit interface; `HttpClient` `client`: non-null transport; `RefitSettings` `settings`: non-null settings.	`object` implementing the interface. For a source-generated disposable interface, disposing the cast implementation also disposes `client`. Throws `InvalidOperationException` when no generated implementation is available on modern .NET.
`ForGenerated(Type refitInterfaceType, string hostUrl, RefitSettings settings)`	Creates an HTTP client with the supplied settings, then resolves the generated implementation for the runtime interface type.	`Type` `refitInterfaceType`: non-null Refit interface; `string` `hostUrl`: non-null, non-whitespace base address; `RefitSettings` `settings`: non-null settings.	`object` implementing the interface. For a source-generated disposable interface, disposing the cast implementation also disposes the created client.
`For<T>(HttpClient client)`	Creates `T` over a shared client with default settings, using an inline generated implementation when registered and otherwise a reflected request builder.	`HttpClient` `client`: transport used for requests.	`T`: implementation for `T`; reflection can build requests when no inline generated implementation is registered. A source-generated `T` that inherits `IDisposable` disposes `client` when disposed.
`For<T>(HttpClient client, RefitSettings? settings)`	Creates `T` over a shared client, preferring an inline generated implementation and otherwise creating a reflected request builder.	`HttpClient` `client`: transport; `RefitSettings` `settings`: nullable settings, where `null` selects defaults.	`T`: implementation for `T`; the reflected path uses the supplied settings. A source-generated `T` that inherits `IDisposable` disposes `client` when disposed.
`For<T>(HttpClient client, IRequestBuilder<T> builder)`	Creates `T` over a shared client with the request builder you supply.	`HttpClient` `client`: transport; `IRequestBuilder<T>` `builder`: request builder for `T`.	`T`: implementation using the supplied request builder. A source-generated `T` that inherits `IDisposable` disposes `client` when disposed.
`For<T>(string hostUrl)`	Creates an HTTP client with default settings, then creates `T`, using generated inline requests when available and reflection otherwise.	`string` `hostUrl`: non-null, non-whitespace base address for the created client.	`T`: implementation for `T`; if `T` inherits `IDisposable`, disposing it also disposes the created client.
`For<T>(string hostUrl, RefitSettings? settings)`	Creates an HTTP client with the selected settings, then creates `T`, using generated inline requests when available and reflection otherwise.	`string` `hostUrl`: non-null, non-whitespace base address; `RefitSettings` `settings`: nullable settings, where `null` selects defaults.	`T`: implementation for `T`; if `T` inherits `IDisposable`, disposing it also disposes the created client.
`For(Type refitInterfaceType, HttpClient client)`	Creates the runtime-selected interface over a shared client with default settings, using generated inline requests when available and reflection otherwise.	`Type` `refitInterfaceType`: interface to implement; `HttpClient` `client`: transport.	`object` implementing `refitInterfaceType`, using default settings. A source-generated disposable interface disposes `client` when its cast implementation is disposed.
`For(Type refitInterfaceType, HttpClient client, RefitSettings? settings)`	Creates the runtime-selected interface over a shared client, preferring generated inline requests and otherwise creating a reflected request builder.	`Type` `refitInterfaceType`: interface to implement; `HttpClient` `client`: transport; `RefitSettings` `settings`: nullable settings, where `null` selects defaults.	`object` implementing `refitInterfaceType`; the reflected path uses the selected settings. A source-generated disposable interface disposes `client` when its cast implementation is disposed.
`For(Type refitInterfaceType, HttpClient client, IRequestBuilder builder)`	Creates the runtime-selected interface with the non-generic request builder you supply.	`Type` `refitInterfaceType`: interface to implement; `HttpClient` `client`: transport; `IRequestBuilder` `builder`: request builder to use.	`object` implementing `refitInterfaceType`, using the supplied builder. A source-generated disposable interface disposes `client` when its cast implementation is disposed.
`For(Type refitInterfaceType, string hostUrl)`	Creates an HTTP client with default settings, then creates the runtime-selected interface, using generated inline requests when available and reflection otherwise.	`Type` `refitInterfaceType`: interface to implement; `string` `hostUrl`: non-null, non-whitespace base address for the created client.	`object` implementing `refitInterfaceType`, using default settings; if that interface inherits `IDisposable`, disposing the cast implementation also disposes the created client.
`For(Type refitInterfaceType, string hostUrl, RefitSettings? settings)`	Creates an HTTP client with the selected settings, then creates the runtime-selected interface, using generated inline requests when available and reflection otherwise.	`Type` `refitInterfaceType`: interface to implement; `string` `hostUrl`: non-null, non-whitespace base address; `RefitSettings` `settings`: nullable settings, where `null` selects defaults.	`object` implementing `refitInterfaceType`; if that interface inherits `IDisposable`, disposing the cast implementation also disposes the created client.

Type	Purpose
`Refit.HttpClientFactoryExtensions`	Static extension class for service-collection and existing-builder registration methods.
`Refit.ISettingsFor`	Interface that exposes a nullable settings reference without a closed Refit interface type.
`Refit.SettingsFor<T>`	Generic DI holder that associates a nullable settings reference with interface type `T`.

Member	Description	Parameters	Returns or value
`RefitSettings`	Holds the serializer, URL/form formatters, request-building options, exception factories, and HTTP-version settings used by a Refit client.	None.	Mutable settings object.
`RefitSettings()`	Creates a complete settings object with Refit's default serializer, formatters, and exception factories.	None.	New settings with the System.Text.Json serializer, default URL, form, and key formatters, plus default exception factories.
`RefitSettings(IHttpContentSerializer contentSerializer)`	Creates settings that use the supplied content serializer and the other defaults.	`IHttpContentSerializer` `contentSerializer`: serializer; must not be `null`.	New settings using the supplied serializer and default URL, form, and key formatters.
`RefitSettings(IHttpContentSerializer contentSerializer, IUrlParameterFormatter? urlParameterFormatter)`	Creates settings with a supplied serializer and URL-value formatter.	`IHttpContentSerializer` `contentSerializer`: required serializer; `IUrlParameterFormatter` `urlParameterFormatter`: formatter or `null` for the default.	New settings using the supplied choices and the default form and key formatters.
`RefitSettings(IHttpContentSerializer contentSerializer, IUrlParameterFormatter? urlParameterFormatter, IFormUrlEncodedParameterFormatter? formUrlEncodedParameterFormatter)`	Creates settings with supplied serializer, URL-value, and form-value formatters.	`IHttpContentSerializer` `contentSerializer`: required serializer; `IUrlParameterFormatter` `urlParameterFormatter`: formatter or `null`; `IFormUrlEncodedParameterFormatter` `formUrlEncodedParameterFormatter`: formatter or `null`.	New settings using the supplied choices and the default key formatter.
`RefitSettings(IHttpContentSerializer contentSerializer, IUrlParameterFormatter? urlParameterFormatter, IFormUrlEncodedParameterFormatter? formUrlEncodedParameterFormatter, IUrlParameterKeyFormatter? urlParameterKeyFormatter)`	Creates settings with supplied serializer and all formatter choices.	`IHttpContentSerializer` `contentSerializer`: required serializer; `IUrlParameterFormatter` `urlParameterFormatter`: formatter or `null`; `IFormUrlEncodedParameterFormatter` `formUrlEncodedParameterFormatter`: formatter or `null`; `IUrlParameterKeyFormatter` `urlParameterKeyFormatter`: formatter or `null`.	New settings; a `null` formatter selects its default.
`RefitSettings.CamelCase()`	Creates settings that serialize JSON and format URL/form keys in camelCase.	None.	New `RefitSettings` using camelCase JSON and URL/form keys.
`RefitSettings.SnakeCase()`	Creates settings that serialize JSON and format URL/form keys in snake_case.	None.	New `RefitSettings` using snake_case JSON and URL/form keys.
`RefitSettings.KebabCase()`	Creates settings that serialize JSON and format URL/form keys in kebab-case.	None.	New `RefitSettings` using kebab-case JSON and URL/form keys.
`AuthorizationHeaderValueGetter`	Supplies a token for a declared `[Authorize]` header that has no token. Generated preparation uses it even with a supplied `HttpClient`; a settings-created handler also uses it for an explicit token.	`Func<HttpRequestMessage, CancellationToken, ValueTask<string>>` or `null`.	Token getter; default `null`. An empty returned token removes the header.
`HttpMessageHandlerFactory`	Supplies the primary handler when Refit creates the `HttpClient`.	`Func<HttpMessageHandler>` or `null`.	Handler factory; default `null`. Refit ignores it when you supply an existing `HttpClient`.
`ExceptionFactory`	Maps unsuccessful HTTP responses to exceptions.	`Func<HttpResponseMessage, ValueTask<Exception?>>`.	Exception factory; default creates Refit API exceptions. A `null` result suppresses the HTTP error.
`DeserializationExceptionFactory`	Maps response-body deserialization failures to exceptions.	`Func<HttpResponseMessage, Exception, ValueTask<Exception?>>` or `null`.	Deserialization exception factory; default `null`. A `null` result suppresses the error.
`ContentSerializer`	Serializes request bodies and deserializes response bodies.	`IHttpContentSerializer`.	Body/reply serializer; default `SystemTextJsonContentSerializer`.
`ReturnTypeAdapters`	Registers custom return wrappers for the opt-in reflection request builder, such as `IObservable<T>`.	Read-only `IList<Type>` property.	Mutable adapter list; default empty. Reflection builds consult it; source-generated builds discover adapters at compile time.
`UrlParameterKeyFormatter`	Formats parameter names used in route, query, and form data.	`IUrlParameterKeyFormatter`.	URL/form key formatter; default `DefaultUrlParameterKeyFormatter`.
`HonorContentSerializerPropertyNamesInQuery`	Chooses whether flattened query names follow serializer property names.	`bool`.	`true` makes flattened query keys honor serializer names; default `true`. `AliasAs` wins in either mode.
`UrlParameterFormatter`	Formats parameter values inserted into URLs.	`IUrlParameterFormatter`.	Path/query value formatter; default `DefaultUrlParameterFormatter`.
`UrlParameterFormatterMap`	Selects URL value formatters by exact runtime type before the general formatter.	Read-only `IDictionary<Type, IUrlParameterFormatter>` property.	Mutable formatter map; default empty. Base classes and interfaces are not searched.
`FormUrlEncodedParameterFormatter`	Formats values written into form-url-encoded request bodies.	`IFormUrlEncodedParameterFormatter`.	Form value formatter; default `DefaultFormUrlEncodedParameterFormatter`.
`CollectionFormat`	Selects how collection values become repeated or joined URL parameters.	`CollectionFormat`.	Collection rendering mode; default `RefitParameterFormatter`.
`Buffered`	Chooses whether request content is buffered before the HTTP send.	`bool`.	Buffer request content before sending; default `false`.
`CaptureRequestContent`	Captures request-body text so an `ApiExceptionBase` can expose it after a failed request.	`bool`.	Retain request-body text in memory; default `false`. Avoid it for large or streamed uploads.
`CaptureMethodArguments`	Stores boxed interface-call arguments in the request options for a handler to inspect.	`bool`.	Retain an `object?[]` for the request lifetime; default `false`.
`MaxExceptionContentLength`	Limits the response-body characters captured while building an API exception.	`int?` characters.	Error-body capture limit; default `null` (unbounded).
`ExceptionRedactor`	Scrubs sensitive data from an `ApiExceptionBase` before Refit returns it.	`Action<ApiExceptionBase>` or `null`.	Exception scrubbing hook; default `null`.
`AllowUnmatchedRouteParameters`	Allows route placeholders without matching method parameters.	`bool`.	Leaves unmatched `{token}` text for later rewriting when `true`; default `false`.
`ValidateHeaders`	Enables framework validation when Refit applies declared headers.	`bool`.	Use framework header parsing; default `false`. Invalid values throw `FormatException` when a request is built.
`UrlResolution`	Selects how relative request paths resolve against `HttpClient.BaseAddress`.	`UrlResolutionMode`.	Base-address resolution mode; default `RefitLegacy`.
`RequestBodySerialization`	Selects how Refit creates JSON request-body content.	`RequestBodySerializationMode`.	JSON body serialization mode; default `Default`. `Buffered` and `Streamed` require `ISynchronousContentSerializer`.
`RequestCompression`	Selects the content encoding applied to every request body.	`RequestCompression`.	Request-body coding; default `None`. A `[Body]` coding overrides this setting.
`RequestCompressionLevel`	Sets the compression effort for compressed request bodies.	`CompressionLevel`.	Compression effort; default `Optimal`.
`RequestCompressionOptions`	Provides per-coding compressor settings that override the compression level for that coding.	`RequestCompressionOptions` or `null` (.NET 9+).	Per-coding compressor settings; default `null`, which uses the compression level.
`HttpRequestMessageOptions`	Copies these local values to every generated request's options on modern .NET, or properties on .NET Framework.	`Dictionary<string, object>` or `null`; `init` only.	Local request values; default `null`. The dictionary remains mutable after initialization.
`TransportExceptionFactory`	Maps exceptions thrown by `HttpClient.SendAsync` to the exception Refit surfaces.	`Func<HttpRequestMessage, Exception, CancellationToken, Exception>`.	Default preserves an `OperationCanceledException` when its token was cancelled; otherwise it wraps the failure in `ApiRequestException`.
`Version`	Sets the HTTP version requested on generated requests.	`Version` (.NET 6+).	Requested HTTP version; default HTTP/1.1.
`VersionPolicy`	Sets the policy used when negotiating the requested HTTP version.	`HttpVersionPolicy` (.NET 6+).	Version negotiation policy; default `RequestVersionOrLower`.

`Enum`	Value	Meaning
`CollectionFormat`	`RefitParameterFormatter` (0)	Use the configured value formatter.
`CollectionFormat`	`Csv` (1), `Ssv` (2), `Tsv` (3), `Pipes` (4)	Comma, space, tab, or pipe separated values.
`CollectionFormat`	`Multi` (5)	Repeat the parameter for each value.
`CollectionFormat`	`Indexed` (6)	Expand object elements with indexed keys.
`RequestBodySerializationMode`	`Default` (0)	Normal asynchronous serialization.
`RequestBodySerializationMode`	`Buffered` (1)	Synchronous serialization into buffered content.
`RequestBodySerializationMode`	`Streamed` (2)	Synchronous serialization to the request stream.
`RequestCompression`	`Default` (0), `None` (1), `GZip` (2), `Brotli` (3), `Zstandard` (4)	Use settings, no coding, gzip, Brotli, or Zstandard. Brotli requires .NET 8; Zstandard requires .NET 11.
`CompressionLevel`	`Optimal` (0), `Fastest` (1), `NoCompression` (2), `SmallestSize` (3)	Compression effort choices used by `RequestCompressionLevel`.
`UrlResolutionMode`	`RefitLegacy` (0), `Rfc3986` (1)	Legacy base-path prepending or RFC 3986 URI resolution.
`System.Net.Http.HttpVersionPolicy`	`RequestVersionOrLower` (0), `RequestVersionOrHigher` (1), `RequestVersionExact` (2)	HTTP version negotiation choices.

Declaration	Description	Parameters and defaults	Return/value
`RequestBuilder.ForType<T>(RefitSettings? settings)`	Resolves the optional reflection factory and creates a strongly typed builder for `T`; `null` settings are passed through to the factory.	`RefitSettings` `settings`: settings for request construction, or `null`. `T` is the Refit API interface.	`IRequestBuilder<T>` for `T`.
`RequestBuilder.ForType<T>()`	Resolves the optional reflection factory and creates a strongly typed builder for `T` with `null` settings.	`T` is the Refit API interface.	`IRequestBuilder<T>` for `T`.
`RequestBuilder.ForType(Type refitInterfaceType, RefitSettings? settings)`	Resolves the optional reflection factory and creates a builder for the supplied Refit interface type.	`Type` `refitInterfaceType`: Refit interface, including a closed generic interface. `RefitSettings` `settings`: settings for request construction, or `null`.	`IRequestBuilder` for `refitInterfaceType`.
`RequestBuilder.ForType(Type refitInterfaceType)`	Calls the settings overload with `null` and creates a builder for the supplied Refit interface type.	`Type` `refitInterfaceType`: Refit interface, including a closed generic interface.	`IRequestBuilder` for `refitInterfaceType`.
`IRequestBuilder.Settings`	Exposes the `RefitSettings` instance used by this builder.	None.	`RefitSettings` used by the builder.
`IRequestBuilder.BuildRestResultFuncForMethod(string methodName, Type[]? parameterTypes = null, Type[]? genericArgumentTypes = null)`	Resolves and caches a delegate for a reflected interface method. The delegate builds the request and follows the method's declared return shape when invoked.	`string` `methodName`: interface method name. `Type[]` `parameterTypes`: declaration-order parameter types, default `null`; required to select among overloads. `Type[]` `genericArgumentTypes`: types used to close a generic method, default `null`.	`Func<HttpClient, object[], object?>`, taking an `HttpClient` and argument array and returning the method's declared result.
`RestService.RegisterGeneratedFactory(Type refitInterfaceType, Func<HttpClient, IRequestBuilder, object> factory)`	Stores a source-generated factory under an interface `Type`; a later registration for the same type replaces it.	`Type` `refitInterfaceType`: interface key. `Func<HttpClient, IRequestBuilder, object>` `factory`: receives the client and a generated-only `IRequestBuilder`.	`void`; stores the factory. Null type or factory throws `ArgumentNullException`.
`RestService.RegisterGeneratedFactory<T>(Func<HttpClient, IRequestBuilder, T> factory)`	Stores a typed source-generated factory under `typeof(T)`.	`Func<HttpClient, IRequestBuilder, T>` `factory`: receives the client and generated-only builder and returns `T`. `T` is the Refit interface.	`void`; stores the typed factory. A null factory throws `ArgumentNullException`.
`RestService.RegisterGeneratedSettingsFactory<T>(Func<HttpClient, RefitSettings, T> factory)`	Stores a typed source-generated factory that receives settings directly, so generated clients can build requests inline without reflection.	`Func<HttpClient, RefitSettings, T>` `factory`: receives the client and settings and returns `T`. `T` is the Refit interface.	`void`; stores the settings factory. A null factory throws `ArgumentNullException`.
`IRequestBuilder`	Defines the settings property and dynamic method-delegate operation used by request builders.	None.	Interface implemented by reflection and generated-only builders.
`IRequestBuilder<T>`	Carries the target API interface type `T` while inheriting the untyped builder contract.	`T` is the Refit API interface.	`IRequestBuilder`.
`RequestBuilder`	Provides static entry points that resolve the optional reflection request-builder factory.	None.	Static class.

Attribute	HTTP method	Common use
`[Get(path)]`	GET	Read a resource.
`[Post(path)]`	POST	Submit data or create a resource.
`[Put(path)]`	PUT	Replace a resource.
`[Patch(path)]`	PATCH	Change part of a resource.
`[Delete(path)]`	DELETE	Remove a resource.
`[Head(path)]`	HEAD	Read reply headers without a reply body.
`[Options(path)]`	OPTIONS	Ask what operations a service accepts.

Member	Description	Parameters	Returns or value
`HttpMethodAttribute`	Base attribute for declaring the HTTP method and route template used by a Refit interface method.	None. Abstract class.	Attribute type inherited by Refit's built-in HTTP method attributes.
`HttpMethodAttribute(string path)`	Stores the route template for an HTTP operation.	`string` `path`: route template.	Initializes the base attribute with the supplied path.
`HttpMethodAttribute.Method`	Identifies the HTTP verb represented by the attribute.	None. Abstract getter.	`HttpMethod` for the operation.
`HttpMethodAttribute.Path`	Holds the route template Refit combines with method parameters.	None publicly; protected setter for derived attributes.	`string` route template supplied to the constructor or changed by a subclass.
`DeleteAttribute`	Attribute that declares a DELETE request on an interface method.	None. Sealed attribute for methods.	Attribute type inherited from `HttpMethodAttribute`.
`DeleteAttribute(string path)`	Declares a DELETE route with the supplied template.	`string` `path`: route template.	Initializes a DELETE route attribute.
`DeleteAttribute.Method`	Supplies the HTTP method for a DELETE route.	None.	`HttpMethod.Delete`.
`GetAttribute`	Attribute that declares a GET request on an interface method.	None. Sealed attribute for methods.	Attribute type inherited from `HttpMethodAttribute`.
`GetAttribute(string path)`	Declares a GET route with the supplied template.	`string` `path`: route template.	Initializes a GET route attribute.
`GetAttribute.Method`	Supplies the HTTP method for a GET route.	None.	`HttpMethod.Get`.
`HeadAttribute`	Attribute that declares a HEAD request on an interface method.	None. Sealed attribute for methods.	Attribute type inherited from `HttpMethodAttribute`.
`HeadAttribute(string path)`	Declares a HEAD route with the supplied template.	`string` `path`: route template.	Initializes a HEAD route attribute.
`HeadAttribute.Method`	Supplies the HTTP method for a HEAD route.	None.	`HttpMethod.Head`.
`OptionsAttribute`	Attribute that declares an OPTIONS request on an interface method.	None. Sealed attribute for methods.	Attribute type inherited from `HttpMethodAttribute`.
`OptionsAttribute(string path)`	Declares an OPTIONS route with the supplied template.	`string` `path`: route template.	Initializes an OPTIONS route attribute.
`OptionsAttribute.Method`	Supplies the HTTP method for an OPTIONS route.	None.	`HttpMethod` whose method name is `OPTIONS`.
`PatchAttribute`	Attribute that declares a PATCH request on an interface method.	None. Sealed attribute for methods.	Attribute type inherited from `HttpMethodAttribute`.
`PatchAttribute(string path)`	Declares a PATCH route with the supplied template.	`string` `path`: route template.	Initializes a PATCH route attribute.
`PatchAttribute.Method`	Supplies a custom `HttpMethod` whose name is `PATCH`.	None.	HTTP method named `PATCH`.
`PathPrefixAttribute`	Attribute that prepends a shared route prefix to methods on an interface.	None. Sealed attribute for interfaces.	Interface attribute carrying a shared route prefix.
`PathPrefixAttribute(string prefix)`	Stores the prefix Refit applies to the interface's method routes.	`string` `prefix`: shared route prefix.	Initializes an interface route-prefix attribute.
`PathPrefixAttribute.Prefix`	Exposes the prefix supplied to the constructor.	None. Read-only.	`string` route prefix.
`PostAttribute`	Attribute that declares a POST request on an interface method.	None. Sealed attribute for methods.	Attribute type inherited from `HttpMethodAttribute`.
`PostAttribute(string path)`	Declares a POST route with the supplied template.	`string` `path`: route template.	Initializes a POST route attribute.
`PostAttribute.Method`	Supplies the HTTP method for a POST route.	None.	`HttpMethod.Post`.
`PutAttribute`	Attribute that declares a PUT request on an interface method.	None. Sealed attribute for methods.	Attribute type inherited from `HttpMethodAttribute`.
`PutAttribute(string path)`	Declares a PUT route with the supplied template.	`string` `path`: route template.	Initializes a PUT route attribute.
`PutAttribute.Method`	Supplies the HTTP method for a PUT route.	None.	`HttpMethod.Put`.
`UrlAttribute`	Attribute that marks a parameter as the complete absolute request URL.	None. Sealed attribute for parameters.	Parameter marker consumed while Refit builds the request.
`UrlAttribute()`	Marks a method parameter as the absolute URL used for the request.	None.	Initializes a URL parameter marker.

`CollectionFormat`	Shape for two string values
`Csv`	`tags=math%2Ccode`
`Ssv`	`tags=math%20code`
`Tsv`	`tags=math%09code`
`Pipes`	`tags=math%7Ccode`
`Multi`	`tags=math&tags=code`
`Indexed`	Object properties such as `people[0].Id=1&people[1].Id=2`.
`RefitParameterFormatter`	Uses the configured formatter. The default query formatter joins values with commas.

Attribute or property	Use
`AliasAs(name)` / `Name`	Sets an explicit parameter or property name.
`Query()`	Keeps the default delimiter and the configured collection format.
`Query(delimiter)` / `Delimiter`	Chooses the text between nested names. The default is `.`.
`Query(delimiter, prefix)` / `Prefix`	Adds a name before flattened properties.
`Query(delimiter, prefix, format)` / `Format`	Also supplies a value format string.
`Query(collectionFormat)` / `CollectionFormat`	Selects a collection format for this argument.
`Query.IsCollectionFormatSpecified`	Tells custom code whether the attribute explicitly chose a collection format.
`Query.TreatAsString`	Uses the object's `ToString()` result instead of flattening its properties.
`Query.SerializeNull`	Sends a null property as an empty value.
`QueryName()`	Sends valueless flags.
`Encoded()`	Keeps caller-escaped text.
`QueryUriFormat(uriFormat)` / `UriFormat`	Sets the final path and query rendering mode.

Member	Description	Parameters	Returns or value
`CollectionFormat`	Selects how a collection becomes query or form text.	None.	enum with the values listed above.
`CollectionFormat.RefitParameterFormatter`	Delegates collection rendering to the configured URL or form formatter.	None.	int value `0`; the default enum value.
`CollectionFormat.Csv`	Joins values with a comma.	None.	int value `1`.
`CollectionFormat.Ssv`	Joins values with a space.	None.	int value `2`.
`CollectionFormat.Tsv`	Joins values with a tab.	None.	int value `3`.
`CollectionFormat.Pipes`	Joins values with a pipe character.	None.	int value `4`.
`CollectionFormat.Multi`	Emits one key-value pair for each collection value.	None.	int value `5`.
`CollectionFormat.Indexed`	Expands each object element under an indexed key such as `items[0].Name`.	None.	int value `6`; scalar elements use comma-separated values.
`AliasAsAttribute`	An attribute that replaces a query parameter or property name with a service-specific name.	Applied to a parameter or property.	Sealed Attribute type.
`AliasAsAttribute(string name)`	Marks a parameter or property with the exact name Refit sends on the wire.	string `name`: wire name.	An attribute whose Name replaces the CLR name.
`AliasAsAttribute.Name`	Returns the alias supplied to the constructor.	None. Read-only.	string wire name.
`EncodedAttribute`	An attribute that tells generated request building to preserve a caller-encoded parameter.	Applied to a parameter.	Sealed Attribute type.
`EncodedAttribute()`	Marks a parameter value as URL-encoded text that Refit appends verbatim.	None.	Attribute for path segments, query values, and `QueryName` flags.
`QueryAttribute`	An attribute that controls query or form field names, scalar formats, and collection formats.	Applied to a parameter or property.	Sealed Attribute type.
`QueryAttribute()`	Uses `.` as the nested-name delimiter and leaves the collection format to client settings.	None.	Attribute with no prefix or value format.
`QueryAttribute(CollectionFormat collectionFormat)`	Selects a collection format for this parameter or property.	CollectionFormat `collectionFormat`: explicit collection mode.	Attribute for which `IsCollectionFormatSpecified` is `true`.
`QueryAttribute(string delimiter)`	Changes the separator between names when Refit flattens a complex value.	string `delimiter`: nested-name separator.	Attribute with the supplied delimiter.
`QueryAttribute(string delimiter, string prefix)`	Changes flattened names to `prefix + delimiter + propertyName`.	string `delimiter`: nested-name separator; string `prefix`: name before flattened properties.	Attribute with the supplied delimiter and prefix.
`QueryAttribute(string delimiter, string prefix, string format)`	Also stores a value format for a scalar query value. It does not apply that format to flattened properties.	string `delimiter`: nested-name separator; string `prefix`: name before flattened properties; string `format`: value format string.	Attribute with the supplied delimiter, prefix, and format.
`QueryAttribute.CollectionFormat`	Gets the selected format, or sets an explicit format that overrides client settings.	None.	CollectionFormat; reads as `RefitParameterFormatter` until set, while `IsCollectionFormatSpecified` distinguishes that unset state.
`QueryAttribute.Delimiter`	Returns the separator that joins the prefix and flattened property name.	None. Read-only.	string, default `"."`.
`QueryAttribute.Format`	Gets or sets the format string for a scalar query value.	None.	string or `null`; default `null`.
`QueryAttribute.IsCollectionFormatSpecified`	Reports whether code assigned `CollectionFormat`, including through the collection-format constructor.	None. Read-only.	bool, default `false`.
`QueryAttribute.Prefix`	Returns the name prepended to each flattened property.	None. Read-only.	string or `null`; default `null`.
`QueryAttribute.SerializeNull`	Controls whether a null property is written as an empty value instead of omitted.	None.	bool, default `false`.
`QueryAttribute.TreatAsString`	Controls whether Refit uses an object's `ToString()` result instead of flattening its properties.	None.	bool, default `false`.
`QueryNameAttribute`	An attribute that creates a presence-style query flag from a parameter value.	Applied to a parameter.	Sealed Attribute type.
`QueryNameAttribute()`	Marks a parameter whose formatted value becomes a bare query flag without `=value`.	None.	Attribute that omits null values and renders collection elements as separate flags.
`QueryUriFormatAttribute`	An attribute that controls how .NET renders a method's final request URI.	Applied to a method.	Sealed Attribute type.
`QueryUriFormatAttribute(UriFormat uriFormat)`	Sets the .NET URI rendering mode for the method's complete path and query.	UriFormat `uriFormat`: final URI rendering mode.	Attribute applied to a method.
`QueryUriFormatAttribute.UriFormat`	Returns the URI rendering mode supplied to the constructor.	None. Read-only.	UriFormat.

Key formatter	`Format("PageSize")`	Settings shortcut
`DefaultUrlParameterKeyFormatter`	`PageSize`	The default settings.
`CamelCaseUrlParameterKeyFormatter`	`pageSize`	`RefitSettings.CamelCase()`
`SnakeCaseUrlParameterKeyFormatter`	`page_size`	`RefitSettings.SnakeCase()`
`KebabCaseUrlParameterKeyFormatter`	`page-size`	`RefitSettings.KebabCase()`

`RequestCompression`	Result
`Default = 0`	The attribute takes coding and level from settings. Settings set to `Default` do not compress.
`None = 1`	No coding; an attribute can opt out of a settings-level coding.
`GZip = 2`	`Content-Encoding: gzip`.
`Brotli = 3`	`Content-Encoding: br` on .NET 8 and later.
`Zstandard = 4`	`Content-Encoding: zstd` on .NET 11 and later.

Input	Form field name	File name sent
A part wrapper with `Name` set	Its `Name`, overriding `[AliasAs]`	Its nonempty `FileName`
A wrapper with `Name = null`	`[AliasAs]`, otherwise parameter name	Its nonempty `FileName`
A wrapper with empty `FileName`	The same field-name rules	The parameter's aliased or declared name
Raw `Stream` or `byte[]`	Aliased or declared parameter name	The same name
Raw `FileInfo`	Aliased or declared parameter name	`FileInfo.Name`
Raw `HttpContent`	Its existing content-disposition metadata	Its existing metadata
A string, formatted value or serialized model	Aliased or declared parameter name	None

Format	Content type	Body shape
`JsonArray`	`application/json`, or another type not listed below	A JSON array such as `[{"id":1,"name":"Ada"}]`.
`JsonLines`	`application/jsonl`, `application/x-ndjson`, or `application/x-jsonlines`	Each line holds a separate JSON value.
`ServerSentEvents`	`text/event-stream`	Each event's `data:` field holds a JSON value.

API	Description	Parameters	Returns and behavior
`IUrlParameterFormatter.Format(object? value, ICustomAttributeProvider attributeProvider, Type type)`	Defines how an implementation converts a URL parameter value.	`value`: `object`; `attributeProvider`: `ICustomAttributeProvider`; `type`: containing `Type`	Returns `string`, or `null` to omit the value.
`IFormUrlEncodedParameterFormatter.Format(object? value, string? formatString)`	Defines how an implementation converts a form-url-encoded field value.	`value`: `object`; `formatString`: `string` format, which may be `null`	Returns `string`, or `null` to omit the field.
`IUrlParameterKeyFormatter.Format(string key)`	Defines how an implementation converts a URL parameter name into its wire key.	`key`: `string` key	Returns the formatted `string` key.
`DefaultUrlParameterKeyFormatter()`	Creates the default key formatter.	None	Creates a formatter whose `Format` method returns each key unchanged.
`DefaultUrlParameterKeyFormatter.Format(string key)`	Applies the identity naming rule to a URL parameter key.	`key`: `string` key	Returns the same key.
`CamelCaseUrlParameterKeyFormatter()`	Creates a key formatter that converts leading uppercase letters to camelCase.	None	Creates a camelCase key formatter.
`CamelCaseUrlParameterKeyFormatter.Format(string key)`	Converts the leading uppercase run of a key to camelCase and leaves keys that do not start with uppercase unchanged.	`key`: `string` key	Returns the camelCase `string` key.
`SnakeCaseUrlParameterKeyFormatter()`	Creates a key formatter that separates words with underscores.	None	Creates a snake_case key formatter.
`SnakeCaseUrlParameterKeyFormatter.Format(string key)`	Converts a key to snake_case.	`key`: `string` key	Returns the snake_case `string` key.
`KebabCaseUrlParameterKeyFormatter()`	Creates a key formatter that separates words with hyphens.	None	Creates a kebab-case key formatter.
`KebabCaseUrlParameterKeyFormatter.Format(string key)`	Converts a key to kebab-case.	`key`: `string` key	Returns the kebab-case `string` key.
`DefaultFormUrlEncodedParameterFormatter()`	Creates the default form-url-encoded value formatter.	None	Creates an invariant-culture formatter that uses `EnumMember` values when available.
`DefaultFormUrlEncodedParameterFormatter.Format(object? value, string? formatString)`	Formats a form value with an optional format string.	`value`: `object`; `formatString`: `string` format, which may be `null`	Returns invariant-culture `string` text, uses an `EnumMember` value when available, and returns `null` for a `null` value.
`DefaultUrlParameterFormatter()`	Creates the default URL value formatter.	None	Creates an invariant-culture formatter with no registered formats.
`DefaultUrlParameterFormatter.AddFormat<TParameter>(string format)`	Registers a format for values whose runtime type is exactly `TParameter`.	`format`: `string` format; `TParameter`: value type	Returns `void`; adding the same type twice throws `ArgumentException`. A non-blank query attribute format takes precedence.
`DefaultUrlParameterFormatter.AddFormat<TContainer, TParameter>(string format)`	Registers a format for an exact `TParameter` value inside an exact `TContainer` type.	`format`: `string` format; `TContainer`: containing type; `TParameter`: value type	Returns `void`; duplicate container/type registrations throw `ArgumentException`. A non-blank query attribute format takes precedence.
`DefaultUrlParameterFormatter.Format(object? value, ICustomAttributeProvider attributeProvider, Type type)`	Formats a URL value using a query attribute format, a container-specific registration, or a general type registration.	`value`: `object`; `attributeProvider`: `ICustomAttributeProvider`; `type`: containing `Type`	Returns invariant-culture `string` text, uses an `EnumMember` value when available, and returns `null` for a `null` value. Throws `ArgumentNullException` when `attributeProvider` is `null`.

API	Description	Parameters	Returns and behavior
`IQueryConverter<T>`	Defines a source-generated converter that writes one parameter's query pairs into a `GeneratedQueryStringBuilder`.	`T`: the declared parameter type handled by the converter.	Interface implemented by a custom query converter; generated request code caches one instance per converter type.
`IQueryConverter<T>.Flatten(T value, string keyPrefix, ref GeneratedQueryStringBuilder builder, RefitSettings settings)`	Writes the non-null query pairs for `value` into `builder`, prefixing each key with `keyPrefix`.	`value`: the declared query value; `keyPrefix`: the prefix from `QueryAttribute`, or an empty string; `builder`: the mutable query builder; `settings`: the active `RefitSettings`. No parameter has a default.	`void`; appends pairs in place. The converter is used by generated requests and is not used by the reflection request builder.
`QueryConverterAttribute`	Marks a query parameter for flattening by a specified `IQueryConverter<T>` implementation.	None. Apply it to a method parameter.	Attribute consumed by source-generated request code; the converter type must have a public parameterless constructor and match the parameter's declared type.
`QueryConverterAttribute(Type converterType)`	Selects the converter type that generated request code instantiates for the annotated parameter.	`converterType`: the `Type` implementing `IQueryConverter<T>`. No default.	`void`; stores `converterType` in `ConverterType`.
`QueryConverterAttribute.ConverterType`	Identifies the converter implementation selected for the annotated parameter.	None; read-only `Type` property.	`Type`; returns the exact type passed to the constructor.
`SystemTextJsonQueryConverter<T>`	Provides a JSON-metadata-based `IQueryConverter<T>` for nested, polymorphic, and otherwise runtime-shaped query values.	`T`: the declared parameter type.	Converter type; reads property names and getters from `SystemTextJsonContentSerializer` metadata.
`SystemTextJsonQueryConverter<T>()`	Creates a JSON metadata query converter for the declared type `T`.	None.	Creates `SystemTextJsonQueryConverter<T>`; it does not capture a value or serializer.
`SystemTextJsonQueryConverter<T>.Flatten(T value, string keyPrefix, ref GeneratedQueryStringBuilder builder, RefitSettings settings)`	Walks the runtime value's JSON metadata and appends scalar, nested-object, and collection values to `builder`.	`value`: the root query value; `keyPrefix`: the prefix for its JSON property names; `builder`: the mutable query builder; `settings`: the active settings, including `CollectionFormat` and `UrlParameterFormatter`. No parameter has a default.	`void`; omits null properties, uses dotted keys for nested objects, formats collection elements according to settings, and stops nested traversal at depth 32. Throws `NotSupportedException` unless `settings.ContentSerializer` is a `SystemTextJsonContentSerializer`.

Attribute or property	Use
`Headers(params string[] headers)` / `Headers`	Shared interface or method headers.
`Header(string header)` / `Header`	One header value from a method argument.
`HeaderCollection()`	A header dictionary from a method argument.
`Authorize(string scheme = "Bearer")` / `Scheme`	An authorization token from a method argument.
`RefitSettings.AuthorizationHeaderValueGetter`	Obtains a missing token before a declared authorized request is sent.
`RefitSettings.ValidateHeaders`	Chooses whether .NET validates header values.

Member	Description	Parameters	Returns or value
`AuthorizeAttribute(string scheme = "Bearer")`	Declares that a method parameter supplies the token for an authorization header.	string `scheme`: authorization scheme; default `"Bearer"`.	Creates an attribute that applies the scheme to a token parameter.
`AuthorizeAttribute.Scheme`	Gets the authorization scheme that Refit places before the token, such as `Bearer` or `Basic`.	None. Read-only.	string scheme supplied to the constructor.
`HeaderAttribute(string header)`	Maps one method argument to a named request header.	string `header`: header declaration.	Creates an attribute that maps one method argument to the named request header.
`HeaderAttribute.Header`	Gets the HTTP header name that receives the method argument value.	None. Read-only.	string header declaration.
`HeaderCollectionAttribute()`	Marks an argument whose dictionary supplies multiple request headers.	None.	Marker attribute for a header dictionary parameter.
`HeadersAttribute(params string[] headers)`	Declares fixed headers that Refit adds to an interface or method request.	`params` string[] `headers`: declarations; null becomes an empty array.	Creates shared interface or method headers from the supplied declarations.
`HeadersAttribute.Headers`	Gets the header declarations Refit applies to interface or method requests.	None. Read-only.	string[] declarations supplied to the constructor.

Key property	Value and use
`InterfaceType`	The top-level interface type for the call.
`MethodName`	The declared method name, such as `BuildAsync`.
`RelativePathTemplate`	The unfilled route, such as `/people/{id}`. Use this stable name for request metrics.
`RestMethodInfo`	Reflected method details when the request-building path supplies them. Generated requests avoid this reflection.
`MethodArguments`	The argument array when `CaptureMethodArguments` is true.
`RequestContent`	The captured body text when `CaptureRequestContent` is true.

Member	Description	Parameters	Returns or value
`PropertyAttribute`	Marks an interface property or method parameter whose value Refit copies to the request's local options or properties.	None.	Attribute type.
`PropertyAttribute()`	Uses the marked property or parameter name as the request option key.	None.	A `PropertyAttribute` instance. The request value is stored under the inferred name.
`PropertyAttribute(string key)`	Uses an explicit request option key instead of the marked property or parameter name.	string `key`: key stored in `Key`.	A `PropertyAttribute` instance.
`PropertyAttribute.Key`	Gets the explicit key selected for the marked property or parameter.	None. Read-only.	Nullable string: the supplied key, or `null` when Refit infers the name.
`HttpRequestMessageOptions`	Provides the string keys that Refit uses for built-in request metadata and optional captured values.	None. Static class.	Static class. Its members return keys for `HttpRequestMessage.Options` or the older `Properties` dictionary.
`HttpRequestMessageOptions.InterfaceType`	Identifies the option that stores the top-level Refit interface type used for the request.	None. Static read-only property.	string `"Refit.InterfaceType"`. The value stored under this key is a `Type`.
`HttpRequestMessageOptions.RestMethodInfo`	Identifies the option that stores reflected method details when the reflection request builder supplies them.	None. Static read-only property.	string `"Refit.RestMethodInfo"`.
`HttpRequestMessageOptions.MethodName`	Identifies the option that stores the declared Refit interface method name.	None. Static read-only property.	string `"Refit.MethodName"`.
`HttpRequestMessageOptions.RelativePathTemplate`	Identifies the option that stores the unfilled route template for logging, metrics, and tracing.	None. Static read-only property.	string `"Refit.RelativePathTemplate"`.
`HttpRequestMessageOptions.RequestContent`	Identifies the option that stores a captured request body string when `CaptureRequestContent` is enabled.	None. Static read-only property.	string `"Refit.RequestContent"`.
`HttpRequestMessageOptions.MethodArguments`	Identifies the option that stores declared method arguments when `CaptureMethodArguments` is enabled.	None. Static read-only property.	string `"Refit.MethodArguments"`. The value stored under this key is an `object?[]`.

`BodySerializationMethod`	Behavior
`Default = 0`	Passes `HttpContent` and streams through. Sends a string as plain text. Uses the configured serializer for other values.
`Serialized = 3`	Uses the configured serializer, including for strings. A JSON string includes quotes.
`UrlEncoded = 2`	Sends form key/value pairs. A dictionary or a generated property map supplies the fields.
`JsonLines = 4`	Sends an enumerable as one serialized value per line. Register the element types with the JSON context.
`Json = 1`	An obsolete name retained for compatibility. Use `Serialized` in new code.

`RequestBodySerializationMode`	Behavior
`Default = 0`	Uses the serializer's usual content method. System.Text.Json uses its async metadata path.
`Buffered = 1`	Uses `ISynchronousContentSerializer` to write a complete byte buffer.
`Streamed = 2`	Uses that interface to write into the outgoing stream without storing the whole body.

API	Description	Parameters or value	Returns and behavior
`BodyAttribute`	Marks one interface-method parameter as the HTTP request body.	Applies to a parameter.	Refit uses the parameter value as `HttpContent`, stream content, plain text, or serialized content according to its type and `SerializationMethod`.
`BodySerializationMethod`	Selects how Refit turns a body value into HTTP content.	Enum values below.	Use with `BodyAttribute` to choose text, serialized, form, or JSON Lines content.
`RequestBodySerializationMode`	Selects how Refit writes serialized JSON request content.	Enum values below.	Configure through `RefitSettings.RequestBodySerialization`.
`RequestCompression`	Selects the content coding applied to a request body.	Enum values below.	Configure a default in `RefitSettings` or override it on `BodyAttribute`.
`RequestCompressionOptions`	Holds optional compressor-specific settings that replace the resolved compression level for each coding.	Available on .NET 9 and later.	Assign it to `RefitSettings.RequestCompressionOptions`.
`TimeoutAttribute`	Applies a per-call timeout to a Refit interface method.	Applies to a method.	A positive timeout cancels the request when it elapses.
`BodySerializationMethod.Default = 0`	Uses Refit's standard body rules.	`0`	Passes `HttpContent` and streams through, sends strings as plain text, and uses the configured serializer for other values.
`BodySerializationMethod.Json = 1`	Retains the former name for serialized content.	`1`; obsolete.	Uses the configured serializer, including for strings. Use `Serialized` in new code.
`BodySerializationMethod.UrlEncoded = 2`	Writes form URL-encoded content.	`2`	A dictionary or object's fields supply form keys and values.
`BodySerializationMethod.Serialized = 3`	Serializes every body value with the configured content serializer.	`3`	Strings use the serializer too, so a JSON string includes its quotes.
`BodySerializationMethod.JsonLines = 4`	Writes newline-delimited JSON.	`4`	Serializes each enumerable item with the configured serializer and writes one item per line.
`RequestBodySerializationMode.Default = 0`	Uses the serializer's asynchronous JSON-content path.	`0`	`System.Text.Json` uses its metadata-based path.
`RequestBodySerializationMode.Buffered = 1`	Serializes JSON into a complete byte buffer before sending.	`1`; requires `ISynchronousContentSerializer`.	Sends `ByteArrayContent` with `Content-Length`; suited to small and medium bodies.
`RequestBodySerializationMode.Streamed = 2`	Writes JSON through a `Utf8JsonWriter` to the request stream.	`2`; requires `ISynchronousContentSerializer`.	Bounds peak memory with pooled chunks and does not set `Content-Length`; suited to large uploads.
`RequestCompression.Default = 0`	Inherits the coding from `RefitSettings.RequestCompression`.	`0`	Uses the settings coding and level.
`RequestCompression.None = 1`	Disables compression for this body.	`1`	Sends no content coding even when settings choose one.
`RequestCompression.GZip = 2`	Compresses the body with gzip.	`2`; every Refit target.	Sends `Content-Encoding: gzip`.
`RequestCompression.Brotli = 3`	Compresses the body with Brotli.	`3`; .NET 8 and later.	Sends `Content-Encoding: br`.
`RequestCompression.Zstandard = 4`	Compresses the body with Zstandard.	`4`; .NET 11 and later.	Sends `Content-Encoding: zstd`.
`BodyAttribute()`	Creates a body parameter attribute without overrides.	None.	Uses `SerializationMethod.Default` and leaves `Buffered` unset so settings decide.
`BodyAttribute(bool buffered)`	Creates a body parameter attribute with an explicit buffering policy.	`buffered`: `bool`.	Sets `Buffered`; serialization remains `Default`.
`BodyAttribute(BodySerializationMethod serializationMethod, bool buffered)`	Creates a body parameter attribute with explicit serialization and buffering policies.	`serializationMethod`: `BodySerializationMethod`; `buffered`: `bool`.	Sets both properties.
`BodyAttribute(BodySerializationMethod serializationMethod)`	Creates a body parameter attribute with an explicit serialization method.	`serializationMethod`: `BodySerializationMethod`.	Sets `SerializationMethod` and leaves `Buffered` unset so settings decide.
`RequestCompressionOptions()`	Creates empty compressor-specific settings.	None; .NET 9 and later.	All coding option properties are `null`, so compression uses its resolved level.
`TimeoutAttribute(int milliseconds)`	Creates a method timeout attribute.	`milliseconds`: `int`.	A positive value applies the per-call deadline; zero or a negative value disables it.
`BodyAttribute.Buffered`	Gets the per-body buffering override.	Read-only `bool?`.	`null` uses `RefitSettings.Buffered`; `true` buffers content before sending and `false` skips it.
`BodyAttribute.SerializationMethod`	Gets the selected body serialization method.	Read-only `BodySerializationMethod`; default `Default`.	Determines how ordinary body values become HTTP content.
`BodyAttribute.Compression`	Gets or sets a method-level request content coding.	Settable `RequestCompression`; default `Default`.	`Default` follows settings, while `None` opts this body out of a settings-level coding.
`BodyAttribute.CompressionLevel`	Gets or sets the compression effort for an explicitly selected coding.	Settable `CompressionLevel`; default `Optimal`.	Refit reads it only when `Compression` names a coding; otherwise settings provide the level.
`RequestCompressionOptions.GZip`	Gets or sets gzip-specific compressor settings.	Settable `ZLibCompressionOptions?`.	A non-null value replaces the resolved level for gzip; `null` uses that level.
`RequestCompressionOptions.Brotli`	Gets or sets Brotli-specific compressor settings.	Settable `BrotliCompressionOptions?`.	A non-null value replaces the resolved level for Brotli; `null` uses that level.
`RequestCompressionOptions.Zstandard`	Gets or sets Zstandard-specific compressor settings.	Settable `ZstandardCompressionOptions?`; .NET 11 and later.	A non-null value replaces the resolved level for Zstandard; `null` uses that level.
`TimeoutAttribute.Milliseconds`	Gets the timeout supplied to `TimeoutAttribute`.	Read-only `int`, in milliseconds.	The effective request deadline exists only when the value is positive.

API	Description	Parameters or value	Returns and behavior
`AttachmentNameAttribute(string name)` (obsolete)	Stores the legacy attachment file-name override. Use a part wrapper for new code.	`name`: `string` to expose through `Name`	Creates the obsolete attribute; using it produces compiler warning `CS0618`.
`AttachmentNameAttribute.Name` (obsolete)	Gets the legacy file-name override.	Read-only `string`	Returns the constructor's `name`.
`ByteArrayPart(byte[] value, string fileName, string? contentType = null, string? name = null)`	Creates a multipart item backed by a byte array.	`value`: `byte[]`; `fileName`: `string`; `contentType`: optional media type, default `null`; `name`: optional form field name, default `null`	Stores the same byte array reference. Throws `ArgumentNullException` when `value` is `null`.
`ByteArrayPart.Value`	Gets the bytes supplied to the constructor.	Read-only `byte[]`	Returns the original array.
`ByteArrayPart.CreateContent()` (protected override)	Builds content for the byte-array part.	None	Returns `ByteArrayContent` over `Value`.
`FileInfoPart(FileInfo value, string fileName, string? contentType = null, string? name = null)`	Creates a multipart item backed by a local file.	`value`: `FileInfo`; `fileName`: `string`; `contentType`: optional media type, default `null`; `name`: optional form field name, default `null`	Stores the file information. Throws `ArgumentNullException` when `value` is `null`; it opens the file only when content is created.
`FileInfoPart.Value`	Gets the source file information.	Read-only `FileInfo`	Returns the original `FileInfo`.
`FileInfoPart.CreateContent()` (protected override)	Opens the source file and builds content for the part.	None	Returns `StreamContent` over a newly opened read stream.
`FormObjectAttribute()`	Marks a complex multipart parameter for property flattening.	None	Causes each public property to become a text part on the reflection request-builder path.
`MultipartAttribute(string boundaryText = "----MyGreatBoundary")`	Marks an HTTP method as multipart and chooses its boundary.	`boundaryText`: `string`, default `"----MyGreatBoundary"`	Stores the boundary used to separate parts.
`MultipartAttribute.BoundaryText`	Gets the boundary configured for the method.	Read-only `string`	Returns the supplied boundary text.
`MultipartItem(string fileName, string? contentType)` (protected)	Initializes a custom multipart item without an explicit form field name.	`fileName`: `string`; `contentType`: optional media type	Stores the file name and content type, with `Name` set to `null`. Throws `ArgumentNullException` for a null file name.
`MultipartItem(string fileName, string? contentType, string? name)` (protected)	Initializes a custom multipart item with optional form field metadata.	`fileName`: `string`; `contentType`: optional media type; `name`: optional form field name	Stores all three values. A null file name throws `ArgumentNullException`.
`MultipartItem.Name`	Gets the explicit form field name for the item.	Read-only `string?`	Returns `null` when the constructor did not receive a name.
`MultipartItem.ContentType`	Gets the optional media type for the item content.	Read-only `string?`	Returns the configured content type, or `null`.
`MultipartItem.FileName`	Gets the file name sent in the multipart disposition.	Read-only `string`	Returns the required file name.
`MultipartItem.ToContent()`	Creates this item's content and applies its nonempty `ContentType`.	None	Returns `HttpContent`. The caller disposes the returned content.
`MultipartItem.CreateContent()` (protected abstract)	Defines how a derived item creates fresh underlying content.	None	Returns `HttpContent`; `ToContent()` applies the configured media type afterward.
`StreamPart(Stream value, string fileName, string? contentType = null, string? name = null)`	Creates a multipart item backed by a caller-owned stream.	`value`: `Stream`; `fileName`: `string`; `contentType`: optional media type, default `null`; `name`: optional form field name, default `null`	Stores the stream without copying it. Throws `ArgumentNullException` when `value` is `null`; disposing its content leaves the caller's stream open.
`StreamPart.Value`	Gets the caller-owned stream.	Read-only `Stream`	Returns the original stream.
`StreamPart.CreateContent()` (protected override)	Wraps the stream without taking ownership of it.	None	Returns `HttpContent` that reads from `Value`.
`AttachmentNameAttribute` (obsolete)	Legacy attribute for naming an attachment.	None	Attribute type; prefer the part wrapper types.
`ByteArrayPart`	Represents byte-array content with multipart metadata.	None	Multipart item type derived from `MultipartItem`.
`FileInfoPart`	Represents file content with multipart metadata.	None	Multipart item type derived from `MultipartItem`.
`FormObjectAttribute`	Marks a complex parameter for multipart property flattening.	None	Parameter attribute type.
`MultipartAttribute`	Marks a method whose body contains named multipart parts.	None	Method attribute type.
`MultipartItem`	Base class for parts that carry a file name and optional content metadata.	None	Abstract type for custom multipart items.
`StreamPart`	Represents caller-owned stream content with multipart metadata.	None	Multipart item type derived from `MultipartItem`.

Refit API reference¶

Clients and settings¶

Create a client¶

Creation overloads¶

Dependency injection¶

Registration overloads¶

Settings¶

Settings reference¶

Request builders¶

Close a generic method¶

Requests¶

Routes and HTTP methods¶

Pick an HTTP method¶

Route attribute reference¶

Query names, values and collections¶

Send a collection¶

Query attribute choices¶

Shared query formatters¶

Choose a key naming rule¶

API reference¶

Query converters¶

API reference¶

Headers and authorization¶

Header order and validation¶

Header attribute reference¶

Local request context¶

Refit's option keys¶

Request context reference¶

Request bodies¶

Choose a serialization method¶

Buffering and serialization modes¶

Compression and ownership¶

API reference¶

Upload files with multipart requests¶

Field names, file names and content types¶

API reference¶

Results¶

Return types¶

Choose a shape¶

Streaming replies¶

Reply formats¶

Response details and success checks¶

Status success and content success differ¶

Response API reference¶

Error bodies and problem details¶

Shared request details¶

Standard validation replies¶

Error API reference¶

Custom return adapters¶

Adapter reference¶

Serialization¶

JSON and generated metadata¶

Serializer capabilities¶

Defaults and fast-path writers¶

Newtonsoft.Json content¶

Method reference¶

XML content¶

Settings reference¶

Method reference¶

Content writers and stream readers¶

Read a stream directly¶

Infer values stored as object¶

API reference¶

Testing¶

Test a Refit client¶

API reference¶

Match outgoing requests¶

Check queries, headers and bodies¶

API reference¶

Supply test replies¶

JSON, text and custom content¶

API reference¶

Inspect requests and verify expectations¶

Verification API reference¶

Simulate network faults¶

Defaults and calculation methods¶

Test code that accepts a response¶

Supply a consistent state¶

Select an error kind¶

Advanced APIs¶

Return type	What happens
`Task`	Sends the request and completes without a result value. See reading one reply.
`Task<T>`	Sends the request and gives you one result to await. See reading one reply.
`ValueTask<T>`	Sends the request and gives you one task-backed result to await. See reading one reply.
`IObservable<T>`	Sends a fresh request per subscription and pushes one result. See querying a reply.
`Task<ApiResponse<T>>`	Gives you a result wrapper with status, headers and a captured error. See keeping status and error details.
`Task<IApiResponse<T>>`	Gives you the typed response wrapper through its interface. See response details.
`Task<IApiResponse>`	Gives you response details without a typed reply body; the wrapper owns live response content. See response details.
`Task<HttpRequestMessage>`	Builds a request and returns it without sending it; the caller owns and must dispose it.
`Task<HttpResponseMessage>`	Returns the live HTTP response; the caller owns and must dispose it.
`Task<HttpContent>`	Returns the live response content; the caller owns and must dispose it.
`Task<Stream>`	Returns the live response body stream; the caller owns and must dispose it.
`Task<ApiResponse<HttpResponseMessage>>`	Wraps the live HTTP response; the caller owns and must dispose it.
`Task<ApiResponse<HttpContent>>`	Wraps the live response content; the caller owns and must dispose it.
`Task<ApiResponse<Stream>>`	Wraps the live response body stream; the caller owns and must dispose it.
`IAsyncEnumerable<T>`	Reads items from one streaming reply; the enumeration owns the live response until it ends.

Property	Meaning
`IsReceived`	A response message exists. False means no response arrived.
`IsSuccessStatusCode`	A response exists and its status is 200–299.
`IsSuccessful`	The status succeeds and `Error` is null.
`HasContent`	`Content` is non-null. For a value type, its default value is also non-null.
`IsSuccessfulWithContent`	Both `IsSuccessful` and `HasContent` are true.
`Content`	The deserialized reply value, or default when unavailable.
`Error`	A captured `ApiExceptionBase`, or null. An unsuccessful manually constructed wrapper may have no error.
`Settings`	The settings supplied to the concrete wrapper. It keeps the same instance.
`RequestMessage`	The request associated with this reply. The interface permits null; the concrete wrapper returns its constructor argument.
`StatusCode`, `ReasonPhrase`, `Version`	The response status, reason text and HTTP version. Null when no response exists.
`Headers`	The response headers. Null when no response exists.
`ContentHeaders`	The body headers, such as its media type. Null when unavailable.

Member	Description	Parameters	Returns or value
`ApiRequestException`	Represents a failure while Refit sends a request before a response arrives.	None.	An `ApiExceptionBase` that retains request context and may wrap the sending exception.
`ApiResponse<T>`	Wraps a deserialized body, HTTP metadata, settings, and a captured error.	`T`: the body type.	A sealed `IApiResponse<T>` that disposes the received response.
`IApiResponse`	Defines status, metadata, error, and disposal members for a Refit response.	None.	The base response contract.
`IApiResponse<T>`	Adds a covariant deserialized body and body-presence checks to `IApiResponse`.	`out T`: the body type read by callers.	The typed response contract.
`ApiResponseExtensions`	Provides success guards for generic and non-generic response interfaces.	None.	A static extension class.
`ApiResponse<T>(HttpRequestMessage request, HttpResponseMessage? response, T? content, RefitSettings settings, ApiExceptionBase? error = null)`	Creates a response wrapper that keeps the request, optional HTTP response, deserialized content, settings, and captured error together.	`HttpRequestMessage` `request`; `HttpResponseMessage?` `response`; `T?` `content`; `RefitSettings` `settings`; `ApiExceptionBase?` `error = null`.	New response wrapper. `response` may be null for a transport failure; `error` defaults to null.
`ApiResponse<T>(HttpResponseMessage response, T? content, RefitSettings settings)`	Creates a wrapper for a received response with no captured error.	`HttpResponseMessage` `response`; `T?` `content`; `RefitSettings` `settings`.	A new wrapper. `response` and `response.RequestMessage` must be non-null.
`ApiResponse<T>(HttpResponseMessage response, T? content, RefitSettings settings, ApiExceptionBase? error)`	Creates a wrapper for a received response and a supplied captured error.	`HttpResponseMessage` `response`; `T?` `content`; `RefitSettings` `settings`; `ApiExceptionBase?` `error`.	A new wrapper. `response` and `response.RequestMessage` must be non-null.
`ApiResponse<T>.Dispose()`	Disposes the received HTTP response once.	None.	`void`; it does not dispose `RequestMessage`.
`ApiResponse<T>.EnsureSuccessStatusCodeAsync()`	Guards only the HTTP status.	None.	`ValueTask<ApiResponse<T>>`; returns this for 2xx. Otherwise it disposes and throws `Error` or a created `ApiException`; with no response it throws `InvalidOperationException`.
`ApiResponse<T>.EnsureSuccessfulAsync()`	Guards the HTTP status and captured error.	None.	`ValueTask<ApiResponse<T>>`; returns this when `IsSuccessful` is true. Failure behavior matches the status guard.
`ApiResponse<T>.HasRequestError(out ApiRequestException? error)`	Checks for a captured transport error and returns it through the out parameter.	`out` `ApiRequestException?` `error`.	`bool`; true when `Error` is a request error.
`ApiResponse<T>.HasResponseError(out ApiException? error)`	Checks for a captured response error and returns it through the out parameter.	`out` `ApiException?` `error`.	`bool`; true when `Error` is a response error.
`ApiResponse<T>.Content`	Stores the deserialized response body, or the default value when no body was read.	None.	`T?`: the stored response body, or `default(T)` when no value was read. For a non-nullable value type, this can be a value such as `0`.
`ApiResponse<T>.ContentHeaders`	Exposes headers belonging to the received response body.	None.	`HttpContentHeaders?`: content headers, or null when no response content exists.
`ApiResponse<T>.Error`	Stores the captured transport, HTTP-status, or deserialization error.	None.	`ApiExceptionBase?`: the captured transport, HTTP, or deserialization error.
`ApiResponse<T>.HasContent`	Reports whether the deserialized Content is non-null.	None.	`bool`; `Content` is non-null.
`ApiResponse<T>.IsSuccessfulWithContent`	Reports whether the response succeeded without an error and has non-null Content.	None.	`bool`: true when the status is successful, no error was captured, and `Content` is non-null.
`ApiResponse<T>.Headers`	Exposes headers from the received HTTP response.	None.	`HttpResponseHeaders?`: the received response headers, or null when no response arrived.
`ApiResponse<T>.IsReceived`	Reports whether an HTTP response message was received.	None.	`bool`: true when an HTTP response arrived.
`ApiResponse<T>.IsSuccessStatusCode`	Reports whether the received status code is in the 2xx range.	None.	`bool`: true when a received response has a 2xx status.
`ApiResponse<T>.IsSuccessful`	Reports whether the status is 2xx and no error was captured; it does not require content.	None.	`bool`: true when the status is 2xx and no error was captured. It does not promise body content.
`ApiResponse<T>.ReasonPhrase`	Exposes the reason phrase returned with the HTTP status.	None.	`string?`: the server reason phrase, or null when none is available.
`ApiResponse<T>.RequestMessage`	Exposes the request associated with the response wrapper.	None.	`HttpRequestMessage`: the request associated with this wrapper.
`ApiResponse<T>.Settings`	Exposes the RefitSettings used to process the response.	None.	`RefitSettings`: the settings instance supplied to the constructor.
`ApiResponse<T>.StatusCode`	Exposes the received HTTP status code, or null when no response arrived.	None.	`HttpStatusCode?`: the received status, or null when no response arrived.
`ApiResponse<T>.Version`	Exposes the HTTP version used by the received response.	None.	`Version?`: the received HTTP version, or null when no response arrived.
`IApiResponse.HasRequestError(out ApiRequestException? error)`	Checks for a captured transport error and returns it through the out parameter.	`out` `ApiRequestException?` `error`.	`bool`: true and assigns the transport error when the request failed before a response; otherwise false and null.
`IApiResponse.HasResponseError(out ApiException? error)`	Checks for a captured response error and returns it through the out parameter.	`out` `ApiException?` `error`.	`bool`: true and assigns the response or body-reading error; otherwise false and null.
`IApiResponse.Headers`	Exposes headers from the received HTTP response.	None.	`HttpResponseHeaders?`: the received response headers, or null when no response arrived.
`IApiResponse.ContentHeaders`	Exposes headers belonging to the received response body.	None.	`HttpContentHeaders?`: headers for the received response body, or null when they are unavailable.
`IApiResponse.IsReceived`	Reports whether an HTTP response message was received.	None.	`bool`: true when an HTTP response arrived.
`IApiResponse.IsSuccessStatusCode`	Reports whether the received status code is in the 2xx range.	None.	`bool`: true when a received response has a 2xx status.
`IApiResponse.IsSuccessful`	Reports whether the status is 2xx and no error was captured; it does not require content.	None.	`bool`: true when the status is 2xx and no error was captured. It does not promise body content.
`IApiResponse.StatusCode`	Exposes the received HTTP status code, or null when no response arrived.	None.	`HttpStatusCode?`: the received status, or null when no response arrived.
`IApiResponse.ReasonPhrase`	Exposes the reason phrase returned with the HTTP status.	None.	`string?`: the server reason phrase, or null when none is available.
`IApiResponse.RequestMessage`	Exposes the request associated with the response wrapper.	None.	`HttpRequestMessage?`: the request that led to the response, or null when unavailable.
`IApiResponse.Version`	Exposes the HTTP version used by the received response.	None.	`Version?`: the received HTTP version, or null when no response arrived.
`IApiResponse.Error`	Stores the captured transport, HTTP-status, or deserialization error.	None.	`ApiExceptionBase?`: a captured transport, HTTP, or deserialization error. An unsuccessful response can have no captured error.
`IApiResponse<T>.Content`	Stores the deserialized response body, or the default value when no body was read.	None.	`T?`: the stored response body, or `default(T)` when no value was read. For a non-nullable value type, this can be a value such as `0`.
`IApiResponse<T>.HasContent`	Reports whether the deserialized Content is non-null.	None.	`bool`: true when `Content` is non-null.
`IApiResponse<T>.IsSuccessfulWithContent`	Reports whether the response succeeded without an error and has non-null Content.	None.	`bool`: true when `IsSuccessful` is true and `Content` is non-null.
`ApiRequestException(HttpRequestMessage message, HttpMethod httpMethod, RefitSettings refitSettings, Exception innerException)`	Creates a transport exception with the request, HTTP method, settings, and supplied message or inner cause.	`HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `RefitSettings` `refitSettings`; `Exception` `innerException`.	New transport exception using the non-null cause's message.
`ApiRequestException(string exceptionMessage, HttpRequestMessage message, HttpMethod httpMethod, RefitSettings refitSettings)`	Creates a transport exception with the request, HTTP method, settings, and supplied message or inner cause.	`string` `exceptionMessage`; `HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `RefitSettings` `refitSettings`.	New transport exception with the supplied message.
`ApiRequestException(string exceptionMessage, HttpRequestMessage message, HttpMethod httpMethod, RefitSettings refitSettings, Exception? innerException)`	Creates a transport exception with the request, HTTP method, settings, and supplied message or inner cause.	`string` `exceptionMessage`; `HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `RefitSettings` `refitSettings`; `Exception?` `innerException`.	New transport exception with the supplied message and optional cause.
`ApiResponseExtensions.EnsureSuccessStatusCodeAsync<T>(IApiResponse<T> response)`	Guards only the HTTP status of a typed response.	`IApiResponse<T>` `response`.	`ValueTask<IApiResponse<T>>`; returns the same response for 2xx. It rejects null, and otherwise throws `Error` or `InvalidOperationException` without disposing.
`ApiResponseExtensions.EnsureSuccessfulAsync<T>(IApiResponse<T> response)`	Guards the HTTP status and captured error of a typed response.	`IApiResponse<T>` `response`.	`ValueTask<IApiResponse<T>>`; returns the same response when `IsSuccessful` is true. Failure behavior matches the status guard.
`ApiResponseExtensions.EnsureSuccessStatusCodeAsync(IApiResponse response)`	Guards only the HTTP status of a non-generic response.	`IApiResponse` `response`.	`ValueTask<IApiResponse>`; returns the same response for 2xx. It rejects null, and otherwise throws `Error` or `InvalidOperationException` without disposing.
`ApiResponseExtensions.EnsureSuccessfulAsync(IApiResponse response)`	Guards the HTTP status and captured error of a non-generic response.	`IApiResponse` `response`.	`ValueTask<IApiResponse>`; returns the same response when `IsSuccessful` is true. Failure behavior matches the status guard.

Property	Meaning
`HttpMethod`	The method supplied for the failed call.
`RequestMessage`	The request, including its headers and local options.
`Uri`	`RequestMessage.RequestUri`, which can be null.
`RefitSettings`	The settings retained for the call and later error-body reading.
`RequestContent`	Captured request-body text when enabled; you can replace it to remove private data.
`HasRequestContent`	The captured text is neither null nor empty. Whitespace counts as present.

`ProblemDetails` property	Meaning
`Type`	A URI identifying the kind of problem; defaults to `about:blank`.
`Title`	A short label for that kind of problem.
`Status`	The status in the JSON document. It does not replace the actual HTTP status.
`Detail`	Text about this occurrence.
`Instance`	A URI identifying this occurrence.
`Errors`	A mutable dictionary from field name to an array of validation messages. Empty by default.
`Extensions`	A mutable dictionary for other JSON properties. Empty by default.

Member	Description	Parameters	Returns or value
`ApiExceptionBase`	Abstract base class for Refit exceptions that retain the failed request, its HTTP method, and the settings used for the call.	None.	Base for request-send and response exceptions.
`ApiExceptionBase(HttpRequestMessage message, HttpMethod httpMethod, RefitSettings refitSettings, Exception innerException)`	Initializes an error with the request context and a required underlying exception.	`HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `RefitSettings` `refitSettings`; `Exception` `innerException`.	Protected base constructor using the non-null cause's message.
`ApiExceptionBase(string exceptionMessage, HttpRequestMessage message, HttpMethod httpMethod, RefitSettings refitSettings)`	Initializes an error with a caller-supplied message and request context.	`string` `exceptionMessage`; `HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `RefitSettings` `refitSettings`.	Protected base constructor with the supplied message.
`ApiExceptionBase(string exceptionMessage, HttpRequestMessage message, HttpMethod httpMethod, RefitSettings refitSettings, Exception? innerException)`	Initializes an error with a caller-supplied message, request context, and optional cause.	`string` `exceptionMessage`; `HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `RefitSettings` `refitSettings`; `Exception?` `innerException`.	Protected base constructor with an optional cause.
`ApiExceptionBase.HttpMethod`	Identifies the HTTP method that Refit used for the failed request.	None.	`HttpMethod`: the method used by the failed call.
`ApiExceptionBase.Uri`	Exposes the request URI when the retained request has one.	None.	`Uri?`: `RequestMessage.RequestUri`.
`ApiExceptionBase.RequestMessage`	Gives access to the live request, including headers and request options.	None.	`HttpRequestMessage`: the request, including its headers and local options.
`ApiExceptionBase.RequestContent`	Holds request-body text captured before sending when `CaptureRequestContent` is enabled.	`string?` value.	Captured request-body text. You can replace it to remove private data.
`ApiExceptionBase.HasRequestContent`	Lets you test whether captured request text is available without checking the property yourself.	None.	`bool`: true when captured request text is not null or empty. Whitespace counts as present.
`ApiExceptionBase.RefitSettings`	Gets the settings that governed the failed call.	None.	`RefitSettings`: settings retained for the call and later error-body reading.
`ApiException`	Represents an error received after the server sent an HTTP response.	None.	Exception with response status, headers, and buffered body text.
`ApiException(HttpRequestMessage message, HttpMethod httpMethod, string? content, HttpStatusCode statusCode, string? reasonPhrase, HttpResponseHeaders headers, RefitSettings refitSettings)`	Initializes a response exception with Refit's status-and-reason message.	`HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `string?` `content`; `HttpStatusCode` `statusCode`; `string?` `reasonPhrase`; `HttpResponseHeaders` `headers`; `RefitSettings` `refitSettings`.	Protected HTTP-response constructor.
`ApiException(HttpRequestMessage message, HttpMethod httpMethod, string? content, HttpStatusCode statusCode, string? reasonPhrase, HttpResponseHeaders headers, RefitSettings refitSettings, Exception? innerException)`	Initializes a response exception with Refit's status-and-reason message and an optional underlying cause.	`HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `string?` `content`; `HttpStatusCode` `statusCode`; `string?` `reasonPhrase`; `HttpResponseHeaders` `headers`; `RefitSettings` `refitSettings`; `Exception?` `innerException`.	Protected HTTP-response constructor with an optional cause.
`ApiException(string exceptionMessage, HttpRequestMessage message, HttpMethod httpMethod, string? content, HttpStatusCode statusCode, string? reasonPhrase, HttpResponseHeaders headers, RefitSettings refitSettings)`	Initializes a response exception with an app-defined message.	`string` `exceptionMessage`; `HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `string?` `content`; `HttpStatusCode` `statusCode`; `string?` `reasonPhrase`; `HttpResponseHeaders` `headers`; `RefitSettings` `refitSettings`.	Protected HTTP-response constructor with the supplied message.
`ApiException(string exceptionMessage, HttpRequestMessage message, HttpMethod httpMethod, string? content, HttpStatusCode statusCode, string? reasonPhrase, HttpResponseHeaders headers, RefitSettings refitSettings, Exception? innerException)`	Initializes a response exception with an app-defined message and an optional underlying cause.	`string` `exceptionMessage`; `HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `string?` `content`; `HttpStatusCode` `statusCode`; `string?` `reasonPhrase`; `HttpResponseHeaders` `headers`; `RefitSettings` `refitSettings`; `Exception?` `innerException`.	Protected HTTP-response constructor with the supplied message and optional cause.
`ApiException.Create(HttpRequestMessage message, HttpMethod httpMethod, HttpResponseMessage response, RefitSettings refitSettings)`	Builds an ApiException asynchronously from the failed HTTP response and request metadata.	`HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `HttpResponseMessage` `response`; `RefitSettings` `refitSettings`.	`Task<ApiException>` that captures the unsuccessful response.
`ApiException.Create(HttpRequestMessage message, HttpMethod httpMethod, HttpResponseMessage response, RefitSettings refitSettings, Exception? innerException)`	Builds an ApiException asynchronously from the failed HTTP response and request metadata.	`HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `HttpResponseMessage` `response`; `RefitSettings` `refitSettings`; `Exception?` `innerException`.	`Task<ApiException>` that captures the response and optional cause.
`ApiException.Create(string exceptionMessage, HttpRequestMessage message, HttpMethod httpMethod, HttpResponseMessage response, RefitSettings refitSettings)`	Builds an ApiException asynchronously from the failed HTTP response and request metadata.	`string` `exceptionMessage`; `HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `HttpResponseMessage` `response`; `RefitSettings` `refitSettings`.	`Task<ApiException>` with the supplied message.
`ApiException.Create(string exceptionMessage, HttpRequestMessage message, HttpMethod httpMethod, HttpResponseMessage response, RefitSettings refitSettings, Exception? innerException)`	Builds an ApiException asynchronously from the failed HTTP response and request metadata.	`string` `exceptionMessage`; `HttpRequestMessage` `message`; `HttpMethod` `httpMethod`; `HttpResponseMessage` `response`; `RefitSettings` `refitSettings`; `Exception?` `innerException`.	`Task<ApiException>` with the supplied message and optional cause.
`ApiException.GetContentAsAsync<T>()`	Deserializes buffered response text through the configured asynchronous content serializer.	None; `T` is the requested error-body type.	`Task<T?>`; asynchronous deserialization.
`ApiException.GetContentAs<T>()`	Deserializes buffered response text through the configured synchronous content serializer.	None; `T` is the requested error-body type.	`T?`; synchronous deserialization or `NotSupportedException`.
`ApiException.TryGetContentAs<T>(out T? content)`	Tries synchronous error-body deserialization without letting parsing or serializer-support failures escape.	`out T?` `content`.	`bool`; false for absent, unsupported, or invalid content.
`ApiException.StatusCode`	Identifies the HTTP status sent by the server.	None.	`HttpStatusCode`: the received HTTP response status.
`ApiException.ReasonPhrase`	Preserves the optional reason phrase sent with the HTTP status.	None.	`string?`: the server reason phrase, if supplied.
`ApiException.Headers`	Provides the response headers retained from the failed response.	None.	`HttpResponseHeaders`: the received response headers.
`ApiException.ContentHeaders`	Provides headers belonging to the buffered response body.	None; protected setter.	`HttpContentHeaders?`: headers for the captured response body.
`ApiException.Content`	Holds the raw buffered response body and lets a redactor replace or clear it.	`string?` value.	Captured raw response text. You can replace it to remove private data.
`ApiException.HasContent`	Tests whether `Content` contains non-whitespace response text.	None.	`bool`: true when `Content` is not null, empty, or whitespace.
`DefaultApiExceptionFactory`	Supplies Refit's default conversion from an unsuccessful HTTP response to an `ApiException`.	None.	Response-to-exception factory.
`DefaultApiExceptionFactory(RefitSettings refitSettings)`	Creates the exception factory that turns unsuccessful responses into ApiException instances using the supplied settings.	`RefitSettings` `refitSettings`: settings used to create exceptions.	New factory.
`DefaultApiExceptionFactory.CreateAsync(HttpResponseMessage responseMessage)`	Returns no exception for a successful response, or creates an `ApiException` from an unsuccessful response's retained request.	`HttpResponseMessage` `responseMessage`.	`ValueTask<Exception?>`; null for a successful response.
`ProblemDetails`	Models a standard HTTP problem document, including validation errors and extension fields.	None.	Data object used by `ValidationApiException`.
`ProblemDetails()`	Initializes a problem document with empty `Errors` and `Extensions`, and `Type` set to `about:blank`.	None.	New problem-details object with empty Errors/Extensions and Type "about:blank".
`ProblemDetails.Errors`	Maps each invalid field name to its validation messages.	None; `init` only.	`Dictionary<string, string[]>`; default empty.
`ProblemDetails.Extensions`	Stores JSON properties that are not standard problem-details fields.	None; `init` only.	`IDictionary<string, object>`; default empty.
`ProblemDetails.Type`	Identifies the kind of problem, usually with a URI.	`string?` value.	A URI that identifies the problem kind; default `about:blank`.
`ProblemDetails.Title`	Gives a short human-readable label for the problem kind.	`string?` value.	A short label for the problem kind; default null.
`ProblemDetails.Status`	Carries the status recorded in the JSON problem document.	`int` value.	The status value carried in the problem document; default 0. It does not replace the actual HTTP status.
`ProblemDetails.Detail`	Explains this particular problem occurrence.	`string?` value.	Text about this problem occurrence; default null.
`ProblemDetails.Instance`	Identifies this particular problem occurrence, usually with a URI.	`string?` value.	A URI that identifies this problem occurrence; default null.
`ValidationApiException`	Represents an API error whose body has been parsed as standard problem details.	None.	`ApiException` subtype with typed validation content.
`ValidationApiException(string message)`	Creates a validation exception for app code that has no received problem response to convert.	`string` `message`.	New validation exception with synthetic HTTP context.
`ValidationApiException(string message, Exception innerException)`	Creates a validation exception with an app-defined message and a required cause.	`string` `message`; `Exception` `innerException`: non-null cause.	New validation exception with cause.
`ValidationApiException.Create(ApiException exception)`	Parses the non-blank raw body of an existing API exception as standard problem details.	`ApiException` `exception`: error to convert; it must contain non-whitespace content.	ValidationApiException with ProblemDetails content.
`ValidationApiException.Content`	Exposes the parsed problem document while hiding `ApiException.Content` on a validation exception.	None; private setter.	`ProblemDetails?`: the parsed validation body, or null when this exception was created only with a message.

Member	Description	Parameters	Returns or value
`TReturn IReturnTypeAdapter<TReturn, TResult>.Adapt(Func<CancellationToken, Task<TResult>> invoke)`	Converts the deferred HTTP operation into the custom return shape.	`Func<CancellationToken, Task<TResult>>` `invoke`: deferred HTTP invocation.	`TReturn`: the wrapper value surfaced by the interface method.
`RefitSettings.ReturnTypeAdapters`	Exposes the adapter types that the opt-in reflection request builder uses to create custom return shapes.	None. Read-only `IList<Type>` property; add a closed adapter type or supported open generic definition. Each entry is a `Type`.	Mutable adapter registry, initialized empty. Reflection builds consult it; source generation discovers adapters at compile time.
`IReturnTypeAdapter<TReturn, TResult>`	Defines the contract for converting a deferred HTTP call into the return type exposed by a Refit interface method.	`TReturn`: surfaced wrapper type. `TResult`: deserialized response body type.	Implement `Adapt` to return the wrapper.

Interface	Description
`IHttpContentSerializer`	Defines the required request-body writer, response-body reader and reflected property-name hook.
`ISynchronousContentSerializer`	Adds synchronous buffered and streamed request-body writers. Refit uses them for `Buffered` and `Streamed` request-body modes.
`ISynchronousContentDeserializer`	Adds a reader for an error body that Refit has already buffered as a `string`.
`IStreamingContentSerializer`	Adds an incremental response reader for Refit interface methods that return `IAsyncEnumerable<T>`.

API	Description	Parameters	Returns and behavior
`SystemTextJsonContentSerializer()`	Creates a serializer with Refit's default JSON configuration.	None	Creates and retains a new `JsonSerializerOptions` from `GetDefaultJsonSerializerOptions()`.
`SystemTextJsonContentSerializer(JsonSerializerOptions jsonSerializerOptions)`	Creates a serializer with the supplied JSON configuration.	`jsonSerializerOptions`: `JsonSerializerOptions` that controls JSON conversion and metadata lookup.	Retains and uses the supplied `JsonSerializerOptions` instance.
`SerializerOptions`	Gets the configuration used by this serializer.	None	Returns the same `JsonSerializerOptions` instance passed to the constructor or created by the default constructor.
`GetDefaultJsonSerializerOptions()`	Creates Refit's general-purpose JSON configuration.	None	Returns a fresh mutable `JsonSerializerOptions` with camel-case names, case-insensitive matching, string-number reading, and Refit's object and enum converters.
`GetFastPathJsonSerializerOptions()`	Creates options that can use System.Text.Json's source-generated serialization fast path after you assign generated metadata.	None	Returns a fresh mutable `JsonSerializerOptions` with camel-case names and case-insensitive matching, without Refit converters or custom number handling.
`ToHttpContent<T>(T item)`	Serializes a request value through Refit's normal asynchronous JSON-content path.	`item`: `T`, the request value to serialize.	Returns JSON `HttpContent`. It uses configured generated metadata when available; an interface or abstract `T` without polymorphism configuration uses the non-null value's runtime type.
`ToHttpContentSynchronous<T>(T item)`	Serializes a request value immediately into a buffered JSON body.	`item`: `T`, the request value to serialize.	Returns UTF-8 JSON `HttpContent` with a `ByteArrayContent` body and `application/json; charset=utf-8` content type.
`ToStreamingHttpContent<T>(T item)`	Creates a request body that serializes a value when the HTTP request sends it.	`item`: `T`, the request value to serialize.	Returns `HttpContent` that writes UTF-8 JSON to the request stream with `application/json; charset=utf-8` content type.
`FromHttpContentAsync<T>(HttpContent content, CancellationToken cancellationToken = default)`	Reads a JSON HTTP body as a value.	`content`: `HttpContent`, the response body; `cancellationToken`: `CancellationToken` that cancels the read. Default: `default`.	Returns `Task<T?>` for the deserialized value.
`DeserializeFromString<T>(string content)`	Reads an already buffered JSON string.	`content`: `string`, the JSON text.	Returns `T?`, the deserialized value. Invalid JSON throws `JsonException`.
`DeserializeStreamAsync<T>(Stream stream, StreamingContentFormat format, CancellationToken cancellationToken = default)`	Reads one JSON value at a time from a framed response stream.	`stream`: `Stream`, the response body; `format`: `StreamingContentFormat`, its JSON array, JSON Lines, or SSE framing; `cancellationToken`: `CancellationToken` that cancels enumeration. Default: `default`.	Returns `IAsyncEnumerable<T?>` that yields values as they arrive. See streaming replies.
`GetFieldNameForProperty(PropertyInfo propertyInfo)`	Finds a property's explicit JSON field name for reflected integrations.	`propertyInfo`: `PropertyInfo`, the property to inspect.	Returns the `JsonPropertyNameAttribute` name, or `null` when the property has no such attribute.

Condition	What to do
Generated writer exists	Use `Default` or `Serialization` generation mode. Keep metadata too when you read replies.
No custom converters	Avoid entries in `JsonSerializerOptions.Converters` and `JsonConverter` attributes on the model or its members.
Compatible options	Keep naming, ignored-member and null-handling options aligned with the generated context.
Supported features	Avoid custom encoders, dictionary key policies and reference handling for this path.
Supported number writing	Avoid number handling that changes JSON output, such as `WriteAsString`. `AllowReadingFromString` alone does not block writing.