RapidAPI, an online marketplace where developers can discover application programming interfaces (APIs), has raised $9 million in a series A round of funding led by Andreessen Horowitz, with participation from SV Angel, Green Bay Capital, and Nexmo CEO Tony Jamous.

Founded out of San Francisco in 2015, RapidAPI is a conduit connecting developers with public APIs and allows them to manage all their API connections from a single interface, as well as accessing metrics.

Most technology companies have APIs of some description, and many of these are made publicly available for third-party developers to leverage data or features for their own services, all in the interests of helping disparate applications connect with each other. This is what RapidAPI is all about — helping developers create connections between apps.

How it works

In terms of how APIs find their way onto the RapidAPI platform, well, any API provider can access RapidAPI’s self-serve system, and RapidAPI also builds partnerships with bigger companies to ensure everything goes smoothly.

This is where RapidAPI’s business model takes form. The marketplace platform itself is free for developers to use, but when they wish to pay a company for access to their API, RapidAPI takes a 20 percent cut from the seller. Moreover, RapidAPI offers a premium enterprise version for bigger companies to manage their API consumption, which includes on-premise installation and other advanced features covering security, auditing, and more.

Back in 2016, RapidAPI raised $3.5 million via a seed round of funding that was also led by Andreessen Horowitz, and with another $9 million in the bank the company plans to double down on its core API marketplace product, “making it even more accessible and easy for the developers to use,” according to a statement. RapidAPI also said that it plans to bring more API providers and developers on board.

When we last caught up with RapidAPI in 2016, the company claimed 15 employees, 100 APIs, and around 20,000 users. Today, those figures are pegged at 27, 8,000 and 500,000 respectively, growth that was partly due to RapidAPI’s merger with the Mashape API marketplace last year.

“Developers can work exponentially faster by leveraging existing API technologies, and RapidAPI makes it easy for developers to find, connect, and monitor the APIs,” noted RapidAPI CEO Iddo Gino. “Having grown RapidAPI massively in the past 18 months, we continue investing heavily in product, team, and making it easy for developers to find and connect to the APIs. That way companies can focus on developing breakthrough products while we take care of the seamless API integration.”

APIs are big business, as they enable developers and companies to launch additional revenue streams beyond their own core offerings — such as what Google does via its many APIs, including Maps and Translate.

Above: RapidAPI: Google Translate API

Some companies mainly exist for their API services, as is the case with Twilio, which enables third parties to integrate calls and SMS functionality into their own apps and which raised more than $250 million before it went public on the NYSE back in 2016. Meanwhile, the mighty Google snapped up API management platform Apigee for $625 million in 2016.

Then there’s MuleSoft, which went public on the NYSE last year and offers ProgrammableWeb, a popular API directory that mostly serves as a database, since it doesn’t offer direct API connection and testing functionality.

The API management market was estimated to be worth $600 million in 2016, though some studies project that this figure will rise to more than $2.5 billion by 2021.

“The API has dramatically simplified the way we think about, build, and integrate applications and has become the interface for business,” added Andreessen Horowitz partner Martin Casado. “As the world’s largest online API marketing, RapidAPI is poised to play a transformative role in programming and technology.”

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