Google today said that it’s acquired API.ai, a startup with tools for speech recognition and natural language understanding. Terms of the deal weren’t disclosed.

In addition to its developers tools, Api.ai offers a conversational assistant app with more than 20 million users.

Google did not disclose its plans for integrating the startup’s technology. That will be important, as Google already has tools for natural language understanding and speech recognition, and it has unveiled a Google Assistant that will be available through text messaging interface and the Google Home smart speaker.

“API.AI has a proven track record for helping developers design, build and continuously improve their conversational interfaces,” Google vice president of engineering Scott Huffman wrote in a blog post. “Over 60,000 developers are using Api.ai to build conversational experiences, for environments such as Slack, Facebook Messenger and Kik, to name just a few. Api.ai offers one of the leading conversational user interface platforms and they’ll help Google empower developers to continue building great natural language interfaces.”

Api.ai started in 2010 and launched in 2014. It’s based in Sunnyvale, California. Investors include Alpine Technology Fund, Intel Capital, Motorola Solutions Venture Capital, and SAIC Capital.

“With Google’s knowledge, infrastructure and support, we can make sure you get access to the best available technologies and developments in AI and machine learning,” Api.ai chief executive Ilya Gelfenbeyn wrote in a blog post.

Cisco announced a partnership with Api.ai earlier this year.