How it works
If your site stops working, Pingdom will alert you immediately. Like a watchdog.
Pingdom keeps reports of all errors it detects, and these reports are always available to you online via the Pingdom control panel. You will be able to see when the error/downtime happened, how long it lasted, what kind of error triggered it, and for each outage Pingdom also performs an additional error analysis.
Depending on the kind of error, this extra error analysis includes several steps, including checking that DNS lookups work, traceroutes to locate network problems, saving of the actual HTML page at the time of the error, the header response from the server, and so on. All of it to help you find out what went wrong.
View reports on how your website performs over time
Pingdom has reports that track the performance of your sites and servers through the lifetime of your Pingdom account. They allow you to see various trends in downtime, response time and load time.
It is also possible to enable a public report page that can be viewed by anyone on the Internet, where a selected set of what you monitor shows up.
“I like pingdom - cheap, does what you ask for and very useful evidence when timelineing an outage.”