/tools/http-status puts the full HTTP status code list one search away. Type a number (429), a phrase (gateway timeout), or filter by category — informational, success, redirect, client error, server error — each color-coded.
Each entry shows the canonical reason phrase from the RFC plus a short, practical explanation: when the server actually returns it, what the client should do, and the gotchas (a 301 is permanently cached, a 308 is the verb-preserving sibling, a 451 is the legally-blocked one, etc.).
Includes the less common but useful ones — 103 Early Hints, 207 Multi-Status, 418 I’m a Teapot, 425 Too Early, 451 Unavailable For Legal Reasons. Runs entirely client-side, no network call.