The system isn't perfect. "We can't guarantee that false positives aren't displayed," the company said. For the first 12 months, therefore, Downdetector manually verified every outage before posting it to its site, which gave its developers "a pretty good feeling" of where they needed to improve the software, Sanders said. The service currently has a number of checks built in, like looking at the frequency of certain reports, to help keep its detection accurate.
Still, "we try to err on the cautious side," Sanders said. "We'd rather miss an outage for a small part of the system than be the boy who cries wolf."
Downdetector, which is incorporated in the Netherlands, generates revenue through advertising and by selling some of its data services, such as the email alerts.
The company also operates sites in Germany (Allestorungen.de), the Flemish region of Belgium (Allestoringen.be) and the U.K. (Downdetector.co.uk), and is in the process of building a French website (Touteslespannes.fr), Sanders said.
Similar outage information is offered to the public through sites such as IsItDownRightNow.com and DownRightNow.com, but "we feel we offer more information, such as the nature of the outage," Sanders said, be it Internet-, TV- or phone-based.
Also, "none of those services detected today's outage at CenturyLink," he said, "so we must be doing something right."