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,…