At ProgrammableWeb we've been paying attention to the explosive growth and interest in serverless technologies (E.g. Amazon's Lambda, Google's Google Cloud Functions, and Microsot's Azure Functions). Even Twilio got into the game with its highly specialized serverless offering for Twilio developers.
Have a look at the APIs that peaked the interest of developers, readers, and our own researchers. APIs were chosen according to web traffic, social media mentions, picks from our API directory research team, and hot categories. These interesting APIs were all added to our directory during 2017.