A number with no context
Logs show 502, a test shows 429, a user reports a blank page after a 404. The number tells you who is at fault — client (4xx) or server (5xx) — but only if you decode it.
Look it up without memorizing the table
Paste the code into the HTTP Status Lookup. It returns the class (2xx Success, 3xx Redirect, 4xx Client, 5xx Server), the name, what it means, and the typical fix.
Worked example
429 Too Many Requests means you are rate-limited — honor Retry-After and back off. That is a client-side throttling issue, not a bug. 504 Gateway Timeout means an upstream your server depends on timed out — that is server-side.
Boundaries
- The lookup is a reference for common codes; exotic or vendor-specific codes may not be listed.
- A 2xx does not mean "correct" — only that the request was accepted. Business validation can still fail.
FAQ
301 vs 308? Both are permanent; 308 preserves the request method (use it when a POST must stay a POST).
Slow but 200? A successful status can still be slow — pair the lookup with the Latency Diagnostic.