This tool allows users to inspect the HTTP headers that a web server sends in response to a client's request. HTTP headers contain vital information about the server, the requested resource, and instructions on how the client should handle the response.

List of HTTP status codes

HTTP status response codes are standardized three-digit codes sent by the server to indicate the outcome of a request. They are divided into five classes based on the first digit:

  • 1xx: Informational
  • 2xx: Success
  • 3xx: Redirection
  • 4xx: Client Error
  • 5xx: Server Error

1xx: Informational

These codes are provisional responses indicating that the request was received and the process is continuing. They are rarely seen in everyday browsing.

  • 100 Continue: Indicates that the initial part of a request has been received and the client should continue with the rest of the request.
  • 101 Switching Protocols: Indicates that the server is switching protocols as requested by the client.

2xx: Success

These codes indicate that the server successfully received, understood, and accepted the request.

  • 200 OK: The request has succeeded. This is the standard response for a successful HTTP request.
  • 201 Created: The request has been fulfilled and resulted in a new resource being created.
  • 204 No Content: The server successfully processed the request and is not returning any content.

3xx: Redirection

These codes indicate that further action needs to be taken by the client to complete the request.

  • 301 Moved Permanently: The resource requested has been permanently moved to a new URL.
  • 302 Found: The resource requested is temporarily under a different URL.
  • 304 Not Modified: Indicates that the resource has not been modified since the last request, allowing the client to use cached data.

4xx: Client Error

These codes indicate that the request contains bad syntax or cannot be fulfilled.

  • 400 Bad Request: The server cannot or will not process the request due to an apparent client error.
  • 401 Unauthorized: Authentication is required and has failed or has not yet been provided.
  • 403 Forbidden: The server understood the request but refuses to authorize it.
  • 404 Not Found: The requested resource could not be found on the server.

5xx: Server Error

These codes indicate that the server failed to fulfill a valid request.

  • 500 Internal Server Error: A generic error message indicating that the server encountered an unexpected condition.
  • 502 Bad Gateway: The server received an invalid response from an inbound server.
  • 503 Service Unavailable: The server is currently unavailable (overloaded or down for maintenance).

Why are HTTP Status Codes Important?

Understanding HTTP status codes is crucial for diagnosing and resolving issues on the web. They help web developers and administrators identify problems and ensure that web applications function correctly. For example, a 404 Not Found error can help a developer identify broken links, while a 500 Internal Server Error might indicate issues with the server’s code or configuration.

Moreover, these codes play a vital role in SEO (Search Engine Optimization). Search engines like Google use HTTP status codes to understand the structure and health of a website. A site riddled with 404 errors or experiencing frequent 503 errors may rank lower in search results.

HTTP status response codes are an integral part of web communication, providing essential information about the status of requests. By understanding these codes, you can better navigate the web, diagnose issues, and optimize the performance of web applications. Whether you're a web user, developer, or administrator, familiarity with these codes is a valuable part of your toolkit.