In API testing, HTTP status codes indicate the success or failure of a request. Understanding these codes helps testers identify issues and ensure proper API behavior.
1xx: Informational
100 Continue – The server received the request and is waiting for the rest.
101 Switching Protocols – The server is switching protocols as requested.
2xx: Success
200 OK – The request was successful.
201 Created – A new resource was successfully created.
204 No Content – The request was processed, but there is no content to return.
3xx: Redirection
301 Moved Permanently – The resource has been permanently moved.
302 Found – The resource is temporarily at a different URL.
304 Not Modified – The resource has not changed since the last request.
4xx: Client Errors
400 Bad Request – The server cannot process the request due to client error.
401 Unauthorized – Authentication is required.
403 Forbidden – Access is denied even with authentication.
404 Not Found – The requested resource does not exist.
429 Too Many Requests – The user has sent too many requests in a given time.
5xx: Server Errors
500 Internal Server Error – A generic server error occurred.
502 Bad Gateway – The server received an invalid response from an upstream server.
503 Service Unavailable – The server is temporarily unable to handle the request.
504 Gateway Timeout – The server did not receive a response in time from another server.
Why HTTP Status Codes Matter in API Testing
Help identify issues like authentication failures, incorrect endpoints, or rate limits.
Ensure APIs return expected responses for different scenarios.
Assist in debugging and improving API reliability.