Rest API Headers

In this tutorial, we will learn about Rest API Headers.

What is a Header?

A Header is a key-value pair that is sent between the client and the server along with the request and response both. Headers are metadata that provide additional information about the request and the response. When we make a request to the server, the server sends back a response with headers.

HTTP Headers

We will divide headers into two categories:
  1. Request Headers: These headers are sent by the client to the server along with the request.
  2. Response Headers: These headers are sent by the server to the client along with the response.

HTTP Request Headers

Here is the list of all HTTP request headers that we use in Rest API:
Header Description
Accept Specifies the media types that the client can understand. For Example application/json or application/xml.
Authorization Contains the credentials required to authenticate the client with the server. For Example Bearer token.
Content-Type Specifies the media type of the request or response. For Example application/json or application/xml.
Content-Length Specifies the length of the request or response. For Example 100 bytes.
Cache-Control Specifies the caching behavior of the request or response. It specifies whether the response can be cached or not. If so then for how long. For Example no-cache or max-age=3600.

HTTP Response Headers

Here is the list of all HTTP response headers that we use in Rest API:
Header Description
Content-Type Specifies the media type of the request or response. For Example application/json or application/xml.
Content-Length Specifies the length of the request or response. For Example 100 bytes.
Cache-Control Specifies the caching behavior of the request or response. It specifies whether the response can be cached or not. If so then for how long. For Example no-cache or max-age=3600.
Set-Cookie Specifies the cookie that the server wants to set in the client. For Example sessionid=12345.
Location Specifies the URL of the resource that the client should redirect to. For Example /home.
Expires Specifies the expiration date of the resource. For Example Tue, 01 Jan 2023 00:00:00 GMT.
Last-Modified Specifies the last modified date of the resource. For Example Tue, 01 Jan 2023 00:00:00 GMT.

Here is the list of all HTTP headers that we use in Rest API:

Header Description
Accept Specifies the media types that the client can understand.
Authorization Contains the credentials required to authenticate the client with the server.
Content-Type Specifies the media type of the request or response.
Content-Length Specifies the length of the request or response.
Cache-Control Specifies the caching behavior of the request or response.
Connection Specifies the connection behavior of the client and the server.
Host Specifies the domain name of the server and the port number where the server is running.
User-Agent Specifies the user agent that is making the request.
Referer Specifies the URL of the webpage that linked to the resource being requested.
Server Specifies the server software that is handling the request.
Set-Cookie Specifies the cookie that the server wants to set in the client.
Location Specifies the URL of the resource that the client should redirect to.
ETag Specifies the entity tag of the resource.
Expires Specifies the expiration date of the resource.
Last-Modified Specifies the last modified date of the resource.
Accept-Encoding Specifies the encoding that the client can understand.
Accept-Language Specifies the language that the client can understand.
Content-Encoding Specifies the encoding of the response.
Content-Language Specifies the language of the response.
WWW-Authenticate Specifies the authentication method that the server requires.
Proxy-Authenticate Specifies the authentication method that the proxy server requires.
Upgrade Specifies the protocol that the client wants to switch to.
Sec-WebSocket-Key Specifies the key that the client uses to establish a WebSocket connection.
Sec-WebSocket-Accept Specifies the key that the server uses to establish a WebSocket connection.
Sec-WebSocket-Protocol Specifies the protocol that the client wants to use for the WebSocket connection.
Sec-WebSocket-Version Specifies the version of the WebSocket protocol that the client wants to use.
Sec-WebSocket-Extensions Specifies the extensions that the client wants to use for the WebSocket connection.
Sec-WebSocket-Protocol Specifies the protocol that the server wants to use for the WebSocket connection.
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Next we will learn about Rest API Media Types.
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