Search any HTTP status code or click for full details on when it occurs and how to handle it.
1xx Informational — request received, continuing. 2xx Success — request completed. 3xx Redirection — further action needed. 4xx Client error — bad request. 5xx Server error — server failed to fulfill request.
Developers usually land on a status code reference mid-debugging session, not while casually browsing. A common trigger is an API returning 403 when 401 was expected, or vice versa — the distinction matters because 401 means "you're not authenticated at all" while 403 means "you're authenticated, but not allowed to do this," and picking the wrong one from your own API can mislead whoever's calling it. Chasing a broken redirect chain is another frequent case: confirming whether a 301 or 302 is being returned, since search engines treat permanent and temporary redirects very differently for passing along ranking signals. CORS errors in the browser console often trace back to a preflight request receiving an unexpected status, which is easier to diagnose once you know what each code in the 4xx and 5xx range actually implies. Uptime monitoring tools and load balancers also key off specific codes — a 503 typically signals the server is temporarily overloaded or in maintenance, distinct from a 500 which points to an actual application error. Knowing the exact meaning of a code before writing a fix saves time compared to guessing from the number alone.
301 is a permanent redirect — search engines transfer ranking signals to the new URL. 302 is temporary — the original URL stays canonical. Use 301 unless the move is genuinely short-term.
429 "Too Many Requests" means the client hit a rate limit set by the server — the fix is usually to slow down request frequency or add backoff/retry logic.
All standard 1xx-5xx status codes are listed with their meaning, when they typically occur, and how to fix them.
Want more detail? Read How to Use HTTP Status Codes: Practical Guide and Best Practices.