The RapidAPI team. (RapidAPI Photo)

Application programming interfaces, or APIs, are essential building blocks of the online apps and connected services we use everyday. That’s why Microsoft’s venture arm M12 is leading a $25 million investment round for RapidAPI, a San Francisco-based startup that has built a popular API marketplace used by 1 million developers.

RapidAPI helps developers find and connect to more than 10,000 publicly-available APIs. The 50-person company processes 500 billion API calls each month.

“Responding to the torrid growth of the API economy, RapidAPI is changing the way businesses scale with APIs and microservices,” Mony Hassid, general manager and managing director at M12 who has joined the company’s board, said in a statement. “We are excited about the potential for RapidAPI to enhance developers’ productivity, streamline duplicative work, and assist to combine API contracts.”

RapidAPI has expanded its offerings from beyond just a public API marketplace. It also sells a software tool used by companies to manage and test their internal APIs.

“We started RapidAPI to help developers better manage and consume external APIs, and now we enable them to share and collaborate on internal APIs too, allowing them to work with greater velocity and efficiency,” Iddo Gino, RapidAPI founder and CEO, said in a statement.

M12 has invested in nearly 100 companies since launching three years ago. The venture arm is focused on startups that can sell to big corporations, much like Microsoft does. Microsoft has also shown a commitment to investing in companies built by developers for developers, driven by the $7.5 billion acquisition of GitHub last year.

Other investors in the Series B round include DNS Capital, Green Bay Capital, and Andreessen Horowitz, which led the company’s $9 million Series A round in March 2018. Total funding to date is $37.5 million.

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