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HTTP Status Code Lookup
Search any HTTP status code and get the official name, RFC description, what it means in practice, and when to use it – instantly.
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HTTP Status Code Lookup – ToolPremier

Look up all HTTP status codes · 1xx 2xx 3xx 4xx 5xx · search by number or keyword · browser-based

How it works
Convert in three steps

1. Enter a status code

Type any HTTP status code (200, 301, 404, 500, etc.) or search by name or keyword - not found, redirect, unauthorized.

2. Read the explanation

See the official RFC name, a plain-English explanation of what the code means, when it is returned, and how it differs from similar codes.

3. Browse by category

Explore all codes by class - 1xx informational, 2xx success, 3xx redirection, 4xx client errors, 5xx server errors - to find the right code for your API response.

FAQ
Common questions
401 Unauthorized means the request lacks valid authentication credentials – the user is not logged in or the provided token is invalid. 403 Forbidden means the server understands the request and the user may be authenticated, but they do not have permission to access the resource. In practice: 401 = who are you, 403 = I know who you are, but you cannot go there.
301 Moved Permanently tells the browser and search engines that the resource has moved to a new URL permanently – search engines transfer link equity to the new URL and update their index. 302 Found is a temporary redirect – the resource is temporarily at a different URL, and search engines keep the original URL indexed. Always use 301 for permanent URL changes and SEO purposes.
400 Bad Request is the general-purpose client error code for malformed requests – wrong syntax, invalid parameters, missing required fields. 422 Unprocessable Entity is more specific: the request syntax is correct and well-formed, but the semantic content fails validation – for example, a date field that is formatted correctly but represents an impossible date. Use 422 for validation failures when the format itself is valid.
500 Internal Server Error means something went wrong on the server – an unhandled exception, a crash, or a bug. 503 Service Unavailable means the server is deliberately unable to handle the request right now – typically due to maintenance, overload, or a dependency being down. 503 should include a Retry-After header when the downtime is scheduled. From a monitoring perspective, 500s indicate bugs; 503s indicate capacity or availability events.
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About the HTTP Status Code Lookup
HTTP status codes appear everywhere in web development – in browser DevTools, server logs, API responses, monitoring dashboards, and error handling code. Most developers know the common ones by heart (200, 404, 500), but the less common codes require a quick reference. This lookup covers the full registry of status codes from the relevant RFCs, with plain-English explanations that go beyond the official name to explain when a code is returned, how it differs from similar codes, and when to use it in your own API responses. Search by number, by name, or browse by class.
Benefits
  • Full RFC registry coverage - all 1xx, 2xx, 3xx, 4xx, and 5xx codes documented.
  • Plain-English explanations - goes beyond the official name to explain real-world usage.
  • Comparison guidance - explains how easily confused codes differ (401 vs 403, 301 vs 302, 400 vs 422).
  • Search by code number or keyword - find the right code without knowing the number.
Privacy
All lookup runs client-side. No search queries are transmitted to any server.