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."
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