Azure Functions HTTP output bindings

Use the HTTP output binding to respond to the HTTP request sender (HTTP trigger). This binding requires an HTTP trigger and allows you to customize the response associated with the trigger's request.

The default return value for an HTTP-triggered function is:

  • HTTP 204 No Content with an empty body in Functions 2.x and higher
  • HTTP 200 OK with an empty body in Functions 1.x


Both in-process and isolated worker process C# libraries don't require an attribute. C# script instead uses a function.json configuration file as described in the C# scripting guide.

A return value attribute isn't required. To learn more, see Usage.


In the Java functions runtime library, use the HttpOutput annotation to define an output variable other than the default variable returned by the function. This annotation supports the following settings:


This article uses tabs to support multiple versions of the Node.js programming model. The v4 model is generally available and is designed to have a more flexible and intuitive experience for JavaScript and TypeScript developers. For more details about how the v4 model works, refer to the Azure Functions Node.js developer guide. To learn more about the differences between v3 and v4, refer to the migration guide.


The options object passed to the output.http() method currently doesn't support any properties for model v4.


The following table explains the binding configuration properties that you set in the function.json file.

Property Description
type Must be set to http.
direction Must be set to out.
name The variable name used in function code for the response, or $return to use the return value.


To send an HTTP response, use the language-standard response patterns.

The response type depends on the C# mode:

The HTTP triggered function returns an HttpResponseData object or a Task<HttpResponseData>. If the app uses ASP.NET Core integration in .NET Isolated, it could also use IActionResult, Task<IActionResult>, HttpResponse, or Task<HttpResponse>.

For Java, use an HttpResponseMessage.Builder to create a response to the HTTP trigger. To learn more, see HttpRequestMessage and HttpResponseMessage.

For example responses, see the trigger examples.

Next steps