HTTP Status Codes
Complete reference of HTTP status codes with descriptions. Search and filter by code, category, or keyword.
What are HTTP status codes?
HTTP status codes are three-digit numbers returned by a server in response to a client request. They indicate whether the request was successful, redirected, or encountered an error.
What is the difference between 4xx and 5xx errors?
4xx codes indicate client errors (the request was invalid or unauthorized), while 5xx codes indicate server errors (the server failed to fulfill a valid request).
What does a 301 redirect mean?
A 301 status code means the requested resource has been permanently moved to a new URL. Search engines will update their index to the new URL.
What is the most common HTTP status code?
200 OK is the most common, indicating a successful request. 404 Not Found is the most well-known error code, indicating the requested resource does not exist.
How do HTTP status codes work?
When a browser sends a request to a server, the server processes it and returns a status code along with the response. The first digit indicates the category: 1xx (informational), 2xx (success), 3xx (redirection), 4xx (client error), or 5xx (server error).
What is the difference between 301 and 302 redirects?
301 means permanent redirect (search engines transfer ranking to new URL), while 302 means temporary redirect (original URL retains ranking).
How to fix 404 Not Found error?
Check the URL for typos, ensure the page exists, verify the link is correct, or contact the website administrator if the page should exist.
What causes 500 Internal Server Error?
Server misconfiguration, script errors, database connection issues, insufficient permissions, or resource exhaustion can cause 500 errors.
What is the difference between 401 and 403 errors?
401 Unauthorized means authentication is required, while 403 Forbidden means you are authenticated but lack permission to access the resource.
How to debug HTTP status codes?
Use browser developer tools (Network tab), check server logs, verify request headers, test with curl or Postman, and review application error logs.
What are 1xx status codes used for?
1xx codes are informational responses indicating the request was received and processing continues. Examples: 100 Continue, 101 Switching Protocols.
Why do I see 502 Bad Gateway error?
502 occurs when a server acting as a gateway receives an invalid response from an upstream server. Common causes include server overload, network issues, or misconfigured proxy settings.
What is the purpose of 204 No Content?
204 indicates the request succeeded but there is no content to return. Commonly used for DELETE requests or form submissions that don't require a page reload.
How do status codes affect SEO?
301 redirects pass link equity to new URLs, 404s can hurt if important pages are missing, 5xx errors can deindex pages, and proper status codes help search engines understand site structure.
How to Use HTTP Status Codes
Browse a complete reference of HTTP status codes with clear names and descriptions. Everything runs locally in your browser — no data is uploaded anywhere.
- Scroll the table to browse all HTTP status codes with their names and meanings.
- Click one of the category buttons — All, 1xx, 2xx, 3xx, 4xx, or 5xx — to show only that class of codes.
- Type in the Search box (hint: “Search code or description...”) to find a code like 404 or a keyword like redirect.
- Combine a category filter with a search term, for example 4xx plus timeout, to narrow the list quickly.
- Read each entry's description to learn when the code is returned and how to respond to it.
The first digit gives the class: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error — filtering by class is the fastest way to explore.
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