What is this tool?
Search and inspect standard IETF RFC 9110 HTTP status codes, meanings, caching behaviors, and developer troubleshooting actions.
When to use it?
Debug REST API response codes (such as 400, 401, 403, 404, 422, 500, 502), choose semantic HTTP codes for API design, or check cacheability headers.
How does it work?
Runs completely in your browser memory against a structured RFC 9110 dataset with category filtering and keyword search.
Technical Specifications & Standards
Classifies codes into 1xx (Informational), 2xx (Successful), 3xx (Redirection), 4xx (Client Error), and 5xx (Server Error) classes according to RFC 9110 specifications.
Example Conversions
Code: 422
422 Unprocessable Entity: Client syntax is valid but semantic instructions cannot be processed.
Standards & Technical References
Frequently Asked Questions
HTTP 401 Unauthorized means the client must authenticate itself (missing or invalid credentials), whereas HTTP 403 Forbidden means the server recognizes the identity but denies permission.