About this tool
What is it?
A searchable reference of HTTP status codes — what 200, 301, 400, 401, 403, 404, 429, 500 and 503 actually mean, when servers send them, and how clients should react.
How to use it
- Search by code or symptom (“login loop”, “empty response”).
- Read the semantics before “fixing” the wrong layer.
- Copy the correct code for your API responses.
Examples
- 301 vs 302 vs 307 vs 308: which redirect preserves method and permanence?
- 401 (who are you?) vs 403 (I know you, still no).
- 429 with Retry-After for rate-limited clients.
Important limitations
- Codes describe semantics, not causes: a 500 needs server logs, not code memorization.
- Proxies and CDNs can rewrite codes in transit — verify at origin.
- Custom codes outside registries confuse generic clients.
Privacy
Static reference. Nothing transmitted.
Frequently asked questions
301 or 302?
301 permanent (SEO transfers), 302/307 temporary — 307 preserves method strictly.
Why 418?
“I’m a teapot” — an April Fools’ RFC that stuck around as an Easter egg.
What should APIs return on validation errors?
400 with a machine-readable error body, or 422 where your framework prefers it.