Up / Down Check
Website or domain
Reachability, hosting, latency and page resources in one pass.
Report for
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Status & Hosting
What the server answered and what it says it runs.
DNS & Network
Resolved addresses and the network that announces them.
Latency Breakdown
Where the time went on the way to the first byte.
Page Resources
Files the page asks the browser to load.
No check run yet
Enter a domain above to see whether it is up, who hosts it, and how fast it responds.
What an up or down check actually proves
A site is reachable when four separate things work in order: the name resolves to an address, a TCP connection opens on port 443 or 80, the TLS handshake completes, and the server returns a response. This tool reports each stage with its own timing, so a failure points at the stage that broke instead of a single unhelpful verdict.
Most online checkers stop at the HTTP status code. That is not enough. A server can answer 200 with a maintenance page, or answer 503 while the site is genuinely serving traffic from cache. Read the status alongside the body size and the platform headers before drawing a conclusion.
Status codes that mean the site is not really working
| Status | What it usually means |
|---|---|
| 200 | Served normally. Confirm the body is the page you expect, not a placeholder. |
| 301 / 302 | Redirect. Follow the chain to the final URL; the address may have moved permanently. |
| 403 | Reachable but refusing. Often a firewall, a blocklist or a misconfigured file permission. |
| 404 | The host answers but nothing exists at that path. |
| 500 | The application failed. The server is up, the site is not. |
| 502 / 504 | A proxy is up and the process behind it is dead or too slow to answer. |
| 503 | Deliberately unavailable: maintenance, overload or a rate limiter. |
| 520 to 530 | Cloudflare origin errors. The edge is fine and the origin is unreachable or misconfigured. |
A 5xx from one location can be a 200 from another when a CDN caches per region. If your monitoring alarms and your browser looks fine, that gap is the answer.
When the result is wrong
Three situations produce a misleading up or down verdict. A web application firewall can block this server while allowing your browser, which shows as a 403 even though the site is healthy. GeoDNS can route the check to a different datacenter than the one you reach. And a site that answers 200 with an empty body is up by status and broken by content.
Run the check twice and compare the resolved IP each time. If the address changes between runs, the site uses DNS-based load balancing and a single sample describes one backend, not the service.
Frequently asked questions
Is the site down for everyone or just me?
This check runs from our server, so a failure here but success in your browser points at your network, your DNS cache or a firewall. A failure in both places points at the site.
Why does it show down when I can open the site?
A web application firewall may block automated requests while allowing browsers, and geo-routing can send this check to a different backend. Compare the resolved IP to the one your browser uses.
How often should I monitor a site?
Every minute for revenue pages, every five for everything else. Faster polling mostly adds noise because a single failed request is usually a transient packet loss event.
What does the latency breakdown tell me?
DNS time is name resolution, connect time is the TCP handshake, TLS is the certificate exchange and wait is the server thinking. The largest figure names the bottleneck.
Can it check a site behind Cloudflare?
Yes, but the check reaches the edge rather than the origin. A 520 to 530 status means the edge is healthy and the origin is not.