The Complete Guide to HTTP Status Codes

When building scalable APIs, communicating the exact result of a client's request is critical. You shouldn't just rely on JSON error messages; you must use the standard HTTP status codes correctly. This guide breaks down the core codes every backend developer needs to memorize.

The Status Code Matrix

Here is a quick reference table for the most common responses you will implement in your REST or GraphQL APIs:

Code	Status Text	When to Use It
200	`OK`	The request succeeded and data is being returned.
201	`Created`	A new resource was successfully inserted into the database.
400	`Bad Request`	The client sent invalid data (e.g., missing a required email field).
401	`Unauthorized`	The user is not logged in or the JWT token has expired.
403	`Forbidden`	The user is logged in, but lacks the admin permissions to do this.
404	`Not Found`	The requested resource (like an article ID) does not exist.
500	`Internal Error`	Your server crashed or the database query failed unexpectedly.

Implementation Advice

Always default to a 200 series code for success. If you are catching errors in a try/catch block, ensure you are returning a 400 series for user mistakes and a 500 series only when your own code completely fails.