When a browser asks a server for something, the server sends back a status code. The first digit gives you a clue: 2xx is usually a successful response, 4xx often means the request needs attention, and 5xx points to a server-side failure. HTTP Status Codes is a short list to help you read the code.
Look up a missing page
Open the tool and type 404 in the search box. The list should narrow to 404 Not Found. This means the server did not find the resource at that address. Check the URL and the response body before assuming the entire server is down.
Now search for 502. You should see Bad Gateway. That often means a server acting as a gateway or proxy did not get a usable response from the service behind it. Check the proxy and the upstream service rather than only the page in your browser.
What this reference does not tell you
Search works by number or status name, not a full explanation of every cause. The same code can come from different failures. This page does not make a request to your server; inspect the actual request and response when debugging. Read the related HTTP guide for a workflow.
Where your input goes
Processing runs in your browser. The tool does not upload your input to ilham.dev.
Related guide
For more background, read HTTP and API Debugging.
Questions you might have
- When should I return 401 instead of 403?
401means the request lacks valid authentication credentials for the resource; a client may need to authenticate or renew them.403means the server understood the request but refuses it. Do not assume a403always means the client was successfully authenticated; check your application’s access rules.- Does 200 always mean success?
- For a GET, usually. For an API, a 200 carrying an error object is a common and unhelpful habit. Prefer a status code that matches the outcome.