HTTP Status Code Reference

HTTP status codes are three-digit numbers returned by a web server in response to every HTTP request. They tell the client (browser, API consumer, or crawler) whether the request succeeded, failed, or requires further action. Every developer who builds or consumes web APIs needs to understand these codes to debug issues, design proper error handling, and build reliable integrations.

Status codes are grouped into five classes: 1xx (Informational) for provisional responses, 2xx (Success) for successful operations, 3xx (Redirection) for URL changes and caching, 4xx (Client Error) for bad requests or unauthorized access, and 5xx (Server Error) for backend failures. Each class tells you immediately where to look when something goes wrong — is it a client-side issue (4xx) or a server-side problem (5xx)?

This interactive reference covers all standard HTTP status codes from 100 to 511, including WebDAV extensions and rarely-seen codes like 418 (I'm a Teapot). Each entry includes a description, when to use it, common causes, and example response headers. You can search by code number or name, filter by category, and deep-link to any specific status code.

1. Search by code or name — Type a status code number (e.g., "404") or name (e.g., "teapot") in the search box to instantly find it.
2. Filter by category — Click the category tabs (1xx, 2xx, 3xx, 4xx, 5xx) to browse all codes in a specific class.
3. Expand for details — Click any status code card to see its full description, when to use it, common causes, and an example HTTP response header.
4. Share a specific code — Click "🔗 Copy Link" on any expanded card to get a direct URL (with hash fragment) that opens straight to that status code.

• 60+ status codes — Complete coverage from 100 Continue to 511 Network Authentication Required, including WebDAV and experimental codes.
• Usage guidance — Each code includes "When to Use" guidance so you can choose the right status code for your API responses.
• Common causes — Error codes (4xx, 5xx) include typical root causes to help you debug faster.
• Example headers — See actual HTTP response header examples for each status code, including relevant headers like Location, Retry-After, and WWW-Authenticate.
• Deep linking — Share direct links to any status code using URL hash fragments (e.g., #404), useful for documentation and team communication.
• Instant search — Find any code by number or name with real-time filtering, no page reloads needed.

• API design — Choose the correct status code for each endpoint response (201 for created, 204 for deleted, 422 for validation errors).
• Debugging HTTP errors — Look up what a 502, 429, or 413 error means and what typically causes it.
• Learning REST conventions — Understand the difference between 401 vs 403, 301 vs 308, or 400 vs 422.
• Documentation reference — Link directly to status code definitions in your API documentation or team wiki.
• Interview preparation — Review HTTP status codes and their semantics for backend developer interviews.