Application program interface (API) company Mashape announced today that it has closed an $18 million Series B led by Andreessen Horowitz, which includes Andreessen Horowitz General Partner Martin Casado who joined the company as one of its board directors.

The funding also included previous investors CRV and Index Ventures, bringing the company’s total funding to $28 million.

This round reflects Mashape’s growth of its open source API gateway — Kong — and its commercial API gateway that was built off Kong — Mashape Enterprise.

“Think of Kong as the air traffic control to manage, broker, and hold APIs,” said Augusto Marietti, CEO of Mashape. Smaller businesses or startups use Kong for the production aspect of APIs like identification, logging, and authentication rather than designing or building APIs.

However, its commercial version Mashape Enterprise was built on top of the open source version and is coupled with more enterprise capabilities like providing analytics, publishing APIs, onboarding developers, and offering tighter security.

Mashape’s enterprise version of its API gateway is made specifically for enterprises that have many services communicating with each other. Mashape Enterprise holds and manages all of these internal APIs that are exclusive to that particular enterprise. They are used to connect mobile platforms and applications, “and Kong sits in the middle of all of these services,” Marietti said.

“With Kong, Mashape developed an API Gateway that has quickly become the de facto way for developers and DevOps engineers to securely manage and extend micro-services and serverless APIs,” Casado said in an email to SDxCentral.

The Series B will be used to increase engineering support for its products and roll out more enterprise features.

The San Francisco-based company was founded in 2009. In 2015 Mashape open sourced the core technology, which became Kong. And the commercial version was offered in early 2016. Only about 25 percent of Mashape customers use the open source version and the rest use the enterprise version. It currently has about 30 enterprise customers in industries like finance, media, retail, car manufacturing, and healthcare.

Mashape has about 25 employees who are mostly engineers, Marietti said.

As part of Andreessen Horowitz, Casado recently invested in another API company called RapidAPI, which is an online marketplace. RapidAPI’s goal is to create a community to consume and distribute public APIs.