What the uptime checker tests
Paste a web address and our server requests it once, follows any redirects and tells you what came back:
- Site is reachable or Site appears down or unreachable, at a glance.
- URL tested and Final URL, so you can see where redirects took the request.
- HTTP status, the three-digit code the server replied with.
- Response time, in milliseconds, for the whole request.
- Details, when something went wrong, such as "Could not resolve host".
That's one request, from one location, at one moment: a quick answer to "is it down for everyone, or just me?". You get 5 free checks without an account, shared across all the UpMonix tools, and 5 more with your email address.
How to read your results
| Status | What it means | What to do |
|---|---|---|
| 200 | OK: the page loaded | Nothing, unless the page looks wrong |
| 301 / 302 | Redirect; the checker follows it and shows the final URL | Check the final URL is the one you expect |
| 403 | Forbidden: the server refused | Often a firewall or bot filter; are real visitors blocked too? |
| 404 | Not found | Check the address; the checker counts 404 as "down" |
| 500 | Internal server error | Check your error log: often code, a plugin or the database |
| 502 | Bad gateway: a proxy or CDN got no valid answer from your server | Check the server behind the proxy |
| 503 | Service unavailable: overloaded or in maintenance | Check server load and maintenance mode |
| 504 | Gateway timeout: your server was too slow | Look for slow queries or stuck processes |
| — with "Connection error" | No HTTP answer at all | Read Details: DNS, timeout or certificate |
Response time has no single "good" number. Compare it with what's normal for your site; a sudden jump is worth a look even when the status is 200.
Why a site can be "up" for us and down for you
- DNS caching: after a DNS change, your computer or ISP may still hold the old address for a while.
- Your local network: an office firewall, VPN or broadband fault can block one site while it's fine elsewhere.
- CDN regions: a CDN serves visitors from many locations; one location can have trouble while ours is fine.
- Firewalls and bot protection: security rules can block our server (you'll see 403) or block some real visitors while letting us through.
Common causes of downtime
Hosting outage
The server or hosting provider is down: expect a connection error, timeout or 5xx code. Check your host's status page and contact support.
Expired domain
A lapsed domain can stop resolving, taking website and email with it; the checker shows "Could not resolve host". Check the date with our domain expiry checker.
Expired SSL certificate
Your server may be running, but browsers stop visitors at a security warning. Run the SSL checker on the same hostname.
Plugin, theme or update errors
An automatic update can cause a 500 error or a blank page. Roll back the last change, check the error log, and test updates on a copy first.
Suspended hosting ("fake up" pages)
If a hosting account is suspended, for example over an unpaid invoice, the host may show its own notice in place of your site. That page can return 200, so a quick status check says "reachable". Read more in hosting suspension and "fake up" pages.
When a one-off check isn't enough
UpMonix checks your site on a schedule: every 5 minutes on the Free plan, and more often on some paid plans. To avoid false alarms, it waits for 3 failed checks in a row (the default) before opening an incident and emailing you, and it sends a recovery notice once the site is back. Monitoring can also look for expected page content and recognise hosting suspension pages, which a simple status check misses.
The Free plan is free forever for one domain, with no credit card needed. Paid plans add more monitors, faster checks and more alert channels: see pricing. For the detail, read how UpMonix monitoring works.
FAQ
What does a 503 error mean?
503 means "service unavailable": the server is reachable but can't handle the request right now. Common causes are overload, maintenance mode, or an application that has crashed behind a web server or CDN. If it clears within a minute or two, it was probably a brief spike. If it keeps coming back, check server resources and logs.
Why does the checker say up when my visitors say down?
We test from one location, over our own network. Your visitors might be hitting an old DNS answer, a CDN location with problems, a firewall rule that blocks them, or a fault on their own connection. Ask what exactly they see (an error message or code helps) and check again from a phone on mobile data.
How often should a website be checked?
It depends on what an outage costs you. For a shop or booking site, every few minutes is sensible, so you hear about problems before customers do. UpMonix's Free plan checks every 5 minutes, and some paid plans check more often. A manual check now and then isn't enough, because most outages start when nobody is looking.
Does UpMonix check from multiple locations?
No. UpMonix currently monitors from a single external location, and multi-location confirmation isn't enabled. To reduce false alarms it waits, by default, for 3 failed checks in a row before opening an incident, and for 2 successful checks before closing it. This free checker also runs from that one location.
Is this tool free?
Yes. You can run 5 checks without an account, shared across all the UpMonix tools, and add your email address to unlock 5 more. Cookies must be enabled. For checks that run around the clock, create a free UpMonix account; it's free forever for one domain.