Look up what an HTTP status code means

The job

Debugging an integration means translating numeric codes into causes. The common ones are memorable; the long tail — 418, 425, 507, Cloudflare's 52x — is not.

Find the code

Type a number, a class like 4xx, or a keyword like "redirect" or "rate". Each entry gives the standard meaning plus what usually triggers it.

• Non-standard codes are marked as such — 499 is nginx's client-closed, 52x is Cloudflare's origin errors.
• Filter by class when you don't know the exact code: 4xx = the request was wrong, 5xx = the server failed.

Worked example

A payment webhook keeps failing with 422 — the table says Unprocessable Content: the JSON parsed fine but a field failed validation. That's a body problem, not auth (401) or a missing route (404).

Scope

A reference table, not a probe — it doesn't send requests to your server. Covers IANA-registered 1xx–5xx codes plus widely-seen non-standard ones.

• Status codes tell you what happened, not always why — the server log is still the source of truth for the cause.