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 process C# libraries don't require an attribute. C# script uses a function.json configuration file.

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:


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 a type of IActionResult or Task<IActionResult>.

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