HTTP Header Checker

What is an HTTP header?

HTTP headers are components of the Hypertext Transfer Protocol (HTTP) used to exchange information between a client (such as a web browser) and a server during an HTTP request-response cycle. They provide additional details and instructions regarding the request or response being sent.

HTTP headers consist of a key-value pair and are included in the header section of an HTTP message. Each header field begins with the field name, followed by a colon, and then the field value. Multiple headers can be included in an HTTP message, allowing for a variety of information to be conveyed.

Headers can be categorized into two main types:

1. Request Headers: These headers are sent by the client as part of an HTTP request to provide information about the request or to specify additional instructions. Examples of request headers include "User-Agent" to identify the client software, "Accept" to indicate the acceptable media types for the response, and "Authorization" to provide authentication credentials.

2. Response Headers: These headers are sent by the server as part of an HTTP response to provide information about the response or to specify instructions for the client. Examples of response headers include "Content-Type" to indicate the media type of the response content, "Cache-Control" to control caching behavior, and "Location" for redirection instructions.

HTTP headers are a crucial component of the HTTP protocol and provide additional information about the request or response being sent between a client and a server. Here is a brief overview of commonly used HTTP headers:

1. Content-Type: Specifies the media type of the content being sent or received, such as text/html, application/json, or image/png.

2. Content-Length: Indicates the length of the content in bytes.

3. Cache-Control: Specifies caching directives for both clients and intermediary caches to control caching behavior.

4. User-Agent: Identifies the software or user agent (e.g., web browser) making the request.

5. Authorization: Contains authentication credentials required for accessing protected resources.

6. Accept: Specifies the media types that the client can handle in the response, allowing the server to choose an appropriate representation.

7. Location: Used in redirection responses (HTTP 3xx) to indicate the URL to which the client should redirect.

8. X-Frame-Options: Helps prevent clickjacking attacks by specifying whether a web page can be displayed within an iframe.

9. Referer: Indicates the URL of the webpage that linked to the current page.

10. Set-Cookie: Sets an HTTP cookie on the client's browser, used for maintaining session state or storing user-specific information.

11. Server: Identifies the software and version running on the server.

12. ETag: Provides a unique identifier for a specific version of a resource, allowing clients to perform conditional requests.

For checking redirect chains and expanded URLs, use our URL Expander. You can also resolve domain information with the DNS Lookup or IP Address Lookup tools.