API Status Codes

What Are Status Codes?

HTTP status codes are three-digit numbers returned by a server indicating the outcome of a request, grouped into categories by their first digit.

Common Categories

• 2xx (Success): e.g., 200 OK, 201 Created, 204 No Content.
• 3xx (Redirection): e.g., 301 Moved Permanently, 304 Not Modified.
• 4xx (Client Error): e.g., 400 Bad Request, 401 Unauthorized, 404 Not Found.
• 5xx (Server Error): e.g., 500 Internal Server Error, 503 Service Unavailable.

Why Testers Check Status Codes

The status code is often the very first check in an API test — confirming the server understood the request correctly before validating the body content in detail.