HTTP Status Code Reference

HTTP status codes are three-digit numbers returned by a server in response to a client's request. They are defined in RFC 9110 (HTTP Semantics) and organized into five classes based on the first digit. 1xx codes are informational - the request was received and processing continues. 2xx codes indicate success - the request was received, understood, and accepted. 3xx codes indicate redirection - further action is needed to complete the request. 4xx codes indicate client errors - the request contains bad syntax or cannot be fulfilled. 5xx codes indicate server errors - the server failed to fulfill a valid request. Our HTTP status code reference covers all standard codes across all five categories.

1. 1. Search by Code or Name: Type a status code number (e.g. "404"), a name (e.g. "Not Found"), or a keyword (e.g. "rate limit") in the search box to instantly filter the list. All filtering runs locally in your browser.
2. 2. Filter by Category: Use the category dropdown to focus on a specific class of status codes - 1xx Informational, 2xx Success, 3xx Redirection, 4xx Client Errors, or 5xx Server Errors.
3. 3. Expand for Details: Click any status code row to expand it and see the full description, practical use case, a concrete example, and the RFC reference.

• 1xx - Informational: Provisional responses indicating the request was received and processing is continuing. Rarely seen in practice except for 101 (WebSocket upgrade) and 103 (Early Hints for resource preloading).
• 2xx - Success: The most common category. 200 OK is the standard success response. 201 Created is used after resource creation. 204 No Content is used for successful operations with no response body. 206 Partial Content is used for range requests and video streaming.
• 3xx - Redirection: Indicates the client must take additional action. 301 and 308 are permanent redirects (301 may change method, 308 preserves it). 302 and 307 are temporary redirects. 304 Not Modified enables browser caching.
• 4xx - Client Errors: The request contains an error. 400 Bad Request for malformed input. 401 Unauthorized for missing authentication. 403 Forbidden for insufficient permissions. 404 Not Found for missing resources. 429 Too Many Requests for rate limiting.
• 5xx - Server Errors: The server failed to process a valid request. 500 Internal Server Error for unhandled exceptions. 502 Bad Gateway for upstream failures. 503 Service Unavailable for maintenance or overload. 504 Gateway Timeout for upstream timeouts.

Returning the correct HTTP status code is essential for well-designed APIs and websites. Use 200 for successful GET requests that return data. Use 201 after creating a resource with POST. Use 204 for successful DELETE or PUT with no response body. Use 400 for validation errors, 401 for missing authentication, 403 for authorization failures, and 404 for missing resources. Use 422 for semantic validation errors (well-formed but invalid data). Use 429 for rate limiting. Use 500 only for unexpected server errors - never for client errors. Correct status codes improve API usability, enable proper error handling in clients, and help search engines understand your site structure.