HTTP status
Confirms the page returns the code it should. A server that responds with a 500 is down as far as your customers are concerned, and a plain ping would call it healthy. On Pro and Agency it also checks that the page still shows a text you chose, because an error page that answers 200 is not up either.
Every plan, content check on Pro and Agency
SSL certificate
A certificate that quietly lapses is one of the most avoidable outages there is. You hear 30, 14, 7 and 1 days ahead instead of from a browser security screen, and you hear it when a certificate is in date but issued for the wrong name or by an authority browsers do not trust.
Every plan
Response time
Sites rarely fail all at once, they get slow first. Tracking response time turns that slide into a warning instead of a surprise, and tells you when a service is slower than is normal for it, well before it crosses a limit.
Pro and Agency, or a Starter add-on
DNS
When a domain name stops resolving, everything behind it is gone at once, and a record that changes without anyone knowing is how a site ends up somewhere it should not be. We look your name up through two independent DNS services, open an incident when it stops resolving, and tell you when it starts pointing somewhere new. Where the registry publishes it, you also hear in good time that the registration of the name itself is about to run out.
Pro and Agency