We’ve gathered hour-by-hour observations from tens of thousands of ground stations world-wide, in some places going back a hundred years. We expose it as a sort of “time machine” that lets you explore the past weather at any given location. We’ve also used the data to develop statistical forecasts for any day in the future. For example, say you have an outdoor family reunion in 6 months: with the time machine, you can see what the likely temperature and precipitation will be at the exact day and hour.
Their API sounds good, too, though I haven’t taken the plunge on that yet.
Now that we’ve developed a general-purpose weather API, we’re trying to compete with the other weather APIs available around the Internet. We’ve found those APIs to be difficult and clunky to use, so we’ve tried to make our API as streamlined as possible: you can sign up for a developer account without needing a credit card, and start making requests right away—you can worry about payment information when your app is ready. Additionally, we’ve lowered our prices so that we’re competitive with the other data providers out there.