HTTP Status Code Lookup, private by default

Why HTTP status codes matter

HTTP status codes are short signals from a server to a browser, app, crawler, or API client. They explain whether a request succeeded, redirected, failed because of the client, or failed because of the server.

Clear status codes help users, developers, search engines, and monitoring tools understand what happened without guessing from page text alone.

How to read status classes

The first digit describes the broad category. A 2xx code usually means success, 3xx means redirection, 4xx means the request needs client-side attention, and 5xx means the server or upstream path failed.

The exact code still matters. A 401 authentication issue needs a different fix than a 403 permissions issue, and a 503 temporary outage is different from a 500 application exception.

• 2xx codes: successful responses
• 3xx codes: redirects and cache reuse
• 4xx codes: client request, auth, permission, or validation problems
• 5xx codes: server, gateway, upstream, or overload problems

Practical debugging workflow

Start with the status class, then inspect headers, route configuration, auth state, request body, logs, cache rules, and upstream dependencies. For public pages, also check canonical links, sitemap entries, and robots behavior.

A lookup table does not test a real endpoint. Use it to understand the code, then confirm the live response with your browser devtools, logs, monitoring, or command-line checks.