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HTTP Status Codes: Complete Guide from 200 to 503

Complete HTTP status code guide covering all common 1xx-5xx codes, their meanings, use cases, and troubleshooting methods.

HTTP Status Codes Web Development

HTTP status codes are response codes from servers to client requests, divided into 5 categories.

2xx Success

  • 200 OK - Request successful
  • 201 Created - Resource created
  • 204 No Content - Success with no body

3xx Redirection

  • 301 Moved Permanently - Permanent redirect
  • 302 Found - Temporary redirect
  • 304 Not Modified - Use cached version

4xx Client Errors

  • 400 Bad Request - Malformed request
  • 401 Unauthorized - Authentication required
  • 403 Forbidden - Access denied
  • 404 Not Found - Resource not found
  • 429 Too Many Requests - Rate limited

5xx Server Errors

  • 500 Internal Server Error - Server failure
  • 502 Bad Gateway - Gateway error
  • 503 Service Unavailable - Service down

Status Codes That Affect SEO

  • 301/308 communicate a permanent move and should point directly to the preferred URL.
  • 302/307 are appropriate for temporary moves where the original URL remains canonical.
  • 404 is correct for missing pages; 410 more explicitly says the resource was intentionally removed.
  • 429 tells clients they are sending too many requests and should be paired with Retry-After when possible.
  • Persistent 5xx responses can reduce crawling because the server appears unreliable.

A Practical Troubleshooting Workflow

  1. Check the first response and every redirect hop, not only the final page.
  2. Compare browser and crawler User-Agents for cloaking or bot-specific failures.
  3. Inspect Location, caching, authentication, and CDN response headers.
  4. Confirm the final URL returns the expected status and content.
  5. Re-test from the public internet after changing origin or CDN rules.

Run an HTTP status check to compare live responses, response times, and redirect paths across multiple user agents. For a list of pages, use the Bulk URL Checker.

Frequently Asked Questions

Is every 3xx response an error?

No. Redirects are a normal part of the web. Problems arise when the destination is wrong, the chain is unnecessarily long, or redirects form a loop.

Should a missing page return 200 with an error message?

No. A “soft 404” can confuse crawlers and monitoring tools. Return a real 404 or 410 status while still presenting a useful human-readable error page.

For redirected responses, inspect every destination with the URL Redirect Checker rather than judging only the final page.

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