Every time your browser loads a page, the server answers with a three-digit HTTP status code. Learning the handful that matter tells you instantly whether a website is truly broken, merely missing a page, or actively blocking you.
The families
- 2xx — Success. 200 OK means everything worked.
- 3xx — Redirects. 301/302 mean the page moved; browsers follow automatically.
- 4xx — Client-side. The server heard you but says the request is wrong.
- 5xx — Server-side. The website itself has a problem. These mean "down".
The codes that matter
- 403 Forbidden — the server refuses you. Often anti-bot protection (Cloudflare etc.), not an outage.
- 404 Not Found — the page doesn't exist. The site itself is fine.
- 429 Too Many Requests — you're rate-limited. Slow down; the site is alive.
- 500 Internal Server Error — the site's code crashed. Truly down.
- 502 Bad Gateway — a reverse proxy can't reach the real server. Usually a temporary outage.
- 503 Service Unavailable — the server is overloaded or in maintenance. Truly down.
- 504 Gateway Timeout — the backend is too slow. Often an outage in progress.
Which codes mean "the site is down"?
Only the 5xx family (and no response at all) indicate a real outage. 403/429 usually mean the site works fine for normal visitors but is blocking automated traffic — our checker labels these "protected" instead of "down" for exactly that reason.
Want to see a live code for any site right now? Run it through the speed test — it reports the exact HTTP status the server returns.