Title: WP_REST_Server::send_header
Published: December 9, 2015
Last modified: February 24, 2026

---

# WP_REST_Server::send_header( string $key, string $value )

## In this article

 * [Parameters](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#parameters)
 * [Source](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#source)
 * [Related](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#related)
 * [Changelog](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#changelog)

[ Back to top](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#wp--skip-link--target)

Sends an HTTP header.

## 󠀁[Parameters](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#parameters)󠁿

 `$key`stringrequired

Header key.

`$value`stringrequired

Header value.

## 󠀁[Source](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#source)󠁿

    ```php
    public function send_header( $key, $value ) {
    	/*
    	 * Sanitize as per RFC2616 (Section 4.2):
    	 *
    	 * Any LWS that occurs between field-content MAY be replaced with a
    	 * single SP before interpreting the field value or forwarding the
    	 * message downstream.
    	 */
    	$value = preg_replace( '/\s+/', ' ', $value );
    	header( sprintf( '%s: %s', $key, $value ) );
    }
    ```

[View all references](https://developer.wordpress.org/reference/files/wp-includes/rest-api/class-wp-rest-server.php/)
[View on Trac](https://core.trac.wordpress.org/browser/tags/6.9.4/src/wp-includes/rest-api/class-wp-rest-server.php#L1893)
[View on GitHub](https://github.com/WordPress/wordpress-develop/blob/6.9.4/src/wp-includes/rest-api/class-wp-rest-server.php#L1893-L1903)

## 󠀁[Related](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#related)󠁿

| Used by | Description | 
| [WP_REST_Server::send_headers()](https://developer.wordpress.org/reference/classes/wp_rest_server/send_headers/)`wp-includes/rest-api/class-wp-rest-server.php` |

Sends multiple HTTP headers.

  | 
| [WP_REST_Server::serve_request()](https://developer.wordpress.org/reference/classes/wp_rest_server/serve_request/)`wp-includes/rest-api/class-wp-rest-server.php` |

Handles serving a REST API request.

  |

## 󠀁[Changelog](https://developer.wordpress.org/reference/classes/wp_rest_server/send_header/?output_format=md#changelog)󠁿

| Version | Description | 
| [4.4.0](https://developer.wordpress.org/reference/since/4.4.0/) | Introduced. |

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