How to use the HTTP Status Code Lookup
1. Browse all HTTP status codes grouped by category, or use the search box to find a specific code.
2. Search by code number (e.g., "404"), name (e.g., "timeout"), or category (e.g., "5xx").
3. Click the search box and start typing — results filter instantly.
What is it?
HTTP status codes are three-digit numbers returned by web servers to indicate the result of a request. They're grouped by first digit: 1xx are informational responses, 2xx indicate success, 3xx are redirections, 4xx indicate client errors (something the requester did wrong), and 5xx indicate server errors (something went wrong on the server side).
Understanding status codes is fundamental for API development, debugging network requests, configuring server behaviour, and interpreting access logs. The most commonly encountered codes are 200 (OK), 301/302 (redirects), 400 (bad request), 401/403 (auth errors), 404 (not found), and 500 (server error).
Example
404
404 Not Found Meaning: The server cannot find the requested resource. Category: 4xx Client Error Common causes: • Broken URL or deleted page • Mistyped path in code • Missing route definition
Search by number (404), name (timeout), or category (5xx) to quickly find any status code.
Benefits
Understand any HTTP status code during API integration
Look up 422 Unprocessable Entity, 429 Too Many Requests, 503 Service Unavailable — and 50 more — with plain-English explanations.
Debug unexpected API responses without opening documentation
Identify what the server is communicating with any 4xx or 5xx status code before guessing at the cause.
Understand the semantic difference between similar codes
401 vs 403, 301 vs 302, 404 vs 410 — small differences with important implications for caching, SEO, and client error handling.
Reference canonical descriptions when writing error messages
Use the standard status code description to ensure your API error responses match HTTP conventions that clients expect.
Frequently asked questions
What is the difference between 301 and 302 redirects?
301 (Moved Permanently) tells browsers and search engines to permanently update their records — link equity passes to the new URL. 302 (Found) is a temporary redirect — search engines keep the original URL indexed. Use 301 for permanent URL changes, 302 for temporary ones.
What is the difference between 401 and 403?
401 (Unauthorized) means authentication is required — the user is not logged in. 403 (Forbidden) means the user is authenticated but does not have permission to access this resource. Think: 401 = not logged in, 403 = logged in but access denied.
When should I use 422 vs 400?
400 (Bad Request) means the request is malformed — wrong syntax, invalid JSON, missing required headers. 422 (Unprocessable Content) means the request was syntactically correct but semantically invalid — for example, validation errors in a form submission. REST APIs commonly use 422 for validation failures.