🚦 HTTP Status Code Explainer

Search all standard HTTP response status codes (200, 301, 404, 500, 502, 503) with clear plain-English definitions and developer debugging advice.

Free No Signup Required Browser-Based

Showing 16 HTTP Status Codes

200OK
2xx Success

Standard response for successful HTTP requests.

💡 How to Fix / Debug: Request succeeded as expected.
201Created
2xx Success

Request succeeded and a new resource has been created.

💡 How to Fix / Debug: Common with POST or PUT requests.
204No Content
2xx Success

Server successfully processed request but returns no content.

💡 How to Fix / Debug: Common with DELETE requests.
301Moved Permanently
3xx Redirection

Resource has been permanently assigned a new URI.

💡 How to Fix / Debug: Update bookmarks and internal links to the new canonical URL.
302Found (Temporary Redirect)
3xx Redirection

Resource temporarily resides under a different URI.

💡 How to Fix / Debug: Check temporary routing or login redirects.
304Not Modified
3xx Redirection

Client has cached copy; no need to retransmit resource.

💡 How to Fix / Debug: Browser caching working normally via ETag or If-Modified-Since.
400Bad Request
4xx Client Error

Server cannot process request due to malformed syntax.

💡 How to Fix / Debug: Check JSON payload structure, missing required parameters, or invalid headers.
401Unauthorized
4xx Client Error

Authentication is required and has failed or not been provided.

💡 How to Fix / Debug: Pass a valid Bearer token, API key, or login credentials in Authorization header.
403Forbidden
4xx Client Error

Server understands request but refuses to authorize it.

💡 How to Fix / Debug: Verify user permissions, IP whitelists, or API token scope.
404Not Found
4xx Client Error

Origin server did not find a current representation for target resource.

💡 How to Fix / Debug: Verify URL path spelling and verify route exists in router.
405Method Not Allowed
4xx Client Error

HTTP method used (e.g. GET vs POST) is not supported for this endpoint.

💡 How to Fix / Debug: Check API documentation for allowed HTTP methods (GET, POST, PUT, DELETE).
429Too Many Requests
4xx Client Error

User has sent too many requests in a given amount of time (Rate Limited).

💡 How to Fix / Debug: Implement exponential backoff, client caching, or upgrade API rate limit tier.
500Internal Server Error
5xx Server Error

Generic error message when an unexpected condition occurred on server.

💡 How to Fix / Debug: Check backend application crash logs and database connections.
502Bad Gateway
5xx Server Error

Server received an invalid response from upstream server (e.g. Nginx proxy).

💡 How to Fix / Debug: Ensure backend service/daemon is running and listening on specified port.
503Service Unavailable
5xx Server Error

Server currently unable to handle request due to overload or maintenance.

💡 How to Fix / Debug: Check server CPU/memory usage, load balancer health, and retry after brief delay.
504Gateway Timeout
5xx Server Error

Server acting as gateway did not receive timely response from upstream.

💡 How to Fix / Debug: Optimize slow SQL queries, long-running background tasks, or increase proxy timeout.

How to Use HTTP Status Code Explainer

  1. Filter by status category (2xx, 3xx, 4xx, 5xx) or type a code/keyword
  2. Read the description and developer fix recommendations

📖 Technical Encyclopedia & Standards Reference

Search all standard HTTP response status codes (200, 301, 404, 500, 502, 503) with clear plain-English definitions and developer debugging advice. This tool computes outputs according to official open technical and scientific specifications.

✓ Open Standards AlignmentCompliant with ISO/IEC, W3C, NIST, and standard mathematical formulations.
✓ 100% Client-Side / SecureZero server logging. Computations execute entirely in your local browser sandbox.
Explore more formulas in our Tools Encyclopedia & Glossary →

Frequently Asked Questions

What do HTTP status code ranges mean?
1xx is Informational, 2xx is Successful, 3xx is Redirection, 4xx is Client Error (e.g. 404 Not Found), and 5xx is Server Error (e.g. 500 Internal Error).
What is the difference between 401 and 403 status codes?
401 Unauthorized means the user has not authenticated (missing login), while 403 Forbidden means the user is authenticated but lacks required permission.
By OnlineToolHubs Team • September 2026