How our website checks work
Evidence, with clear limits.
WebUpCheck performs one server-side HTTP check when you request it. It does not continuously monitor sites or establish a global outage.
1. Validate and resolve
We accept public HTTP and HTTPS hostnames on standard ports. Credentials and private network addresses are rejected. We resolve A and AAAA records through Cloudflare DNS and validate destinations again after redirects.
2. Request the page
We issue a GET request with a small byte range, cancel the response body, and follow up to five redirects. If the server rejects the range with HTTP 416, we retry without it. The entire upstream check has an eight-second deadline.
3. Explain the response
- Up: the server returned a response below HTTP 400.
- Blocked: HTTP 401, 403, 407, 429 or 451 indicates restricted access.
- Website error: other HTTP 4xx or 5xx responses. A missing page does not mean the whole site is down.
- Unreachable: no destination address was found.
- Inconclusive: timeout, connection failure, DNS service failure or too many redirects.
Understand timing and location
Duration includes DNS resolution and redirects. It is not browser page-load speed. Requests run on Cloudflare infrastructure; a single observation may differ from your network or another region. API results may be cached for up to 30 seconds; use the returned timestamp.
If the site works here but not for you
Try a private browser window, another device, and a different network. Check the service’s official status page. A local DNS problem, regional restriction, extension, login failure or partial outage can explain the difference. Do not disable security software or ignore certificate warnings to force access.
Report a misleading result so we can investigate.