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HTTP Status

Look up HTTP status codes, status lines, related headers, cache notes, and common API troubleshooting hints locally.

Status code, phrase, header, or class

Lookup result

Enter a status code or phrase

Use a code, status line, phrase, header name, or class such as 4xx.

Status code catalog
HTTP Status

Quick start

1
Enter a code, status line, phrase, header, or class
2
Review the lookup result: class, registry status, status line, and related codes
3
Use class filters to narrow the catalog
4
Copy the code or full status line

Common scenarios

API debugging

confirm whether a response points to auth, validation, throttling, or server failure

Redirect review

compare 301, 302, 307, and 308 before changing routes

Incident notes

separate client errors from upstream and overload failures

Header checks

find Retry-After, Location, WWW-Authenticate, Allow, and Content-Range hints

Usage advice

Registered codes come from the local IANA/RFC-oriented table.
Vendor codes such as nginx 499 or Cloudflare 520 are treated as unregistered in v1.
Reason phrases are helpful labels, but clients should branch on numeric codes.

Status lookup boundaries

This tool does not request URLs, follow redirects, or check live uptime.
A status code narrows the symptom; it does not prove the production root cause.
Temporary, obsolete, and unused registry entries stay visible with labels.

Common confusion guide

301 and 308 are permanent; 302 and 307 are temporary; 307 and 308 preserve method semantics.
401 asks for authentication; 403 means authentication may exist but access is forbidden.
404 says not found; 410 says intentionally gone.
400 is a malformed request; 422 is a semantically invalid payload.
429 is client throttling; 503 is temporary service unavailability.
502 is a bad upstream response; 503 is unavailable; 504 is upstream timeout.

Header hints

Location appears with 201 and redirects.
Retry-After is most relevant for 429 and 503.
WWW-Authenticate explains how to satisfy 401.
Allow lists valid methods for 405.
Content-Range appears with 206 and 416.

Privacy and security

Lookup runs in your browser. Query text is saved only as a local session draft.

FAQ

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