HTTP Status Codes You Actually Need to Know

Every API call returns a status code. Most developers only know 200 and 404. Here are the codes that actually matter for building and debugging web applications.

The 2xx Range: Success

Code	Meaning	When to use
200	OK	Standard successful response
201	Created	A new resource was created
204	No Content	Success with no response body

The 3xx Range: Redirection

Code	Meaning	When to use
301	Moved Permanently	The URL has changed forever
304	Not Modified	Use the cached version

The 4xx Range: Client Errors

Code	Meaning	When to use
400	Bad Request	The request is malformed
401	Unauthorized	Authentication is required
403	Forbidden	Authenticated but not allowed
404	Not Found	The resource does not exist
429	Too Many Requests	Rate limit exceeded

The 5xx Range: Server Errors

Code	Meaning	When to use
500	Internal Server Error	Something broke on the server
502	Bad Gateway	The upstream server failed
503	Service Unavailable	The server is overloaded or down

The Common Mistake

Returning 200 for errors. If a request fails validation, return 400. If authentication fails, return 401. Status codes are how clients know what happened without reading the response body.

The fix: use the most specific status code available. A 400 is better than a 500. A 404 is better than a 400 for missing resources.

The Takeaway

HTTP status codes are a language between client and server. Learn the vocabulary, and debugging becomes ten times easier.

Happy coding!