HTTP Status Codes Explained: 200, 301, 404, 500 and What They Really Mean

A plain-English guide to HTTP status codes — what 2xx, 3xx, 4xx and 5xx mean, why a 404 doesn't mean the whole site is down, and how to fix each one.

2xx — success (200 OK)

Server got it, here is the page. 200 is the normal healthy answer; 201/204 appear on APIs.

3xx — redirects (301, 302, 308)

The page moved. Our checker follows up to 5 hops and shows the final URL — redirect loops or chains longer than 5 surface as Issues.

4xx — client errors (404, 403, 429)

404/410: page gone, but the SITE is up — don't call it “down”. 403: server reachable, access denied (bot protection, geo-block). 429: rate-limited, retry later.

5xx — server errors (500, 502, 503, 504)

The origin is reachable but its app/upstream is broken. 502/504 often mean CDN can't reach origin. These read as Issues in our checker and deserve a recheck in 2–5 minutes.

Test it now: run a live check → then re-read your result with this guide. Each check + guide read is another pageview that funds the free tool.

FAQ

Does a 404 mean the website is down?

No — the server answered, so DNS, TCP and TLS all worked. The site is online; that URL isn't.

What is the difference between 502 and 504?

502: upstream sent an invalid response. 504: upstream took too long. Both are origin-side, not your Wi-Fi.