🌐 HTTP Status Code Reference

What This Reference Covers

This reference covers all 60+ standardized HTTP status codes across the five classes. Each entry includes a plain-English description, a practical use case, relevant HTTP request and response headers, a developer tip, and the defining RFC. Use the live search to find any code by number, name, or keyword (e.g. "redirect", "cache", "auth").

• 1xx Informational — provisional responses (Continue, Switching Protocols, Early Hints)
• 2xx Success — request received and fulfilled (200 OK, 201 Created, 204 No Content, 206 Partial)
• 3xx Redirection — further client action needed (301, 302, 303, 307, 308, 304 Not Modified)
• 4xx Client Error — bad request, auth failure, or permissions (400, 401, 403, 404, 422, 429)
• 5xx Server Error — server failed to fulfill a valid request (500, 502, 503, 504)

How to Use This Reference

The reference is fully interactive — no page reload needed:

• Type any keyword or code number in the search box to filter instantly
• Click a category chip (1xx–5xx) to narrow results to a single class
• Click Show details on any card to expand description, use case, headers, and dev tip
• Use the Jump buttons to scroll directly to a category section
• Click the copy icon on any card to copy the status code number to clipboard
• Tags mark codes as common, rare, cacheable, or deprecated

The 5 Classes

HTTP responses are grouped by their first digit. 1xx codes are informational continuations. 2xx signals success. 3xx indicates redirection — further action is required. 4xx means the client made an error. 5xx means the server failed. Knowing the class instantly tells you where to look when debugging: 4xx = fix the request, 5xx = fix the server.

SEO Implications

301 passes full link equity (PageRank) to the new URL and updates Google's index permanently — use for all permanent moves. 302 is temporary and does not transfer equity long-term. Returning 200 for pages with no content (soft-404s) confuses crawlers. Use 410 instead of 404 for intentionally removed content — Google de-indexes 410 pages significantly faster than 404s.

REST API Design

Use 201 when a resource is created, not 200. Return 204 for successful DELETE or PUT with no body. Use 422 for validation errors (semantically invalid input), 401 for missing authentication, and 403 when auth succeeds but permission is denied. Use 429 for rate limiting with a Retry-After header. Never return 200 with an error payload — it breaks client error handling.