HTTP status code reference · Guide
HTTP Status Codes for API Debugging
A status code is the first clue when an API call fails. Reading it well saves debugging time.
Start with the first digit
A 4xx points you at the request — check the URL, body, headers and auth. A 5xx points at the server — check its logs and upstreams. That split alone halves the search space.
Combine with headers and body
The code says what category of failure; the response body and headers often say why. Read them together for the full picture.
Frequently asked questions
Can I use this for production work?
Yes, for inspection, formatting and quick generation. Still review the output before committing it to production code or configuration.
Ready to try it?
Open the free browser-based HTTP status code reference and apply what you just read — no sign-up, runs locally.
Open the HTTP status code reference tool