We haven’t heard much from Fleksy — one of a number of custom keyboards for Android and iOS — lately, and it seems we may have an answer why: It’s been acquired by Pinterest .

But it isn’t a total product acquisition. While the app will continue running (with minimal updates) for the forseeable future, half of the team will be integrated into Pinterest’s product engineering team, the company said. So while there have been a bunch of successful custom keyboards — including SwiftKey, which Microsoft bought for $250 million — it just goes to show how hard the space is, especially with Apple and Google working to expand their keyboards’ capabilities.

Fleksy was an early entry to the iPhone’s custom keyboards, launching after Apple gave developers the opportunity to install keyboards on the iPhone after holding out for years — and letting Google get a potential leg up with better input experiences than the traditional iPhone keyboard. SwiftKey saw that opportunity on Android, making it a popular paid app on Android devices and eventually turning into a $250 million exit.

Keyboards have become an increasingly important battleground for even the largest companies because they literally control the experience of how users input information into any communication app, whether that’s Facebook Messenger or iMessage. But it’s also a challenging space, with the phone creators beginning to throw a lot of resources at development.

Fleksy raised a little over $7 million, with the most recent $2 million financing round happening in October last year — shortly after Apple opened up the keyboard to developers.

The team behind Fleksy also seems like a smart buy for Pinterest. These kinds of smart keyboards require a mastery of data capture and mining, such as understanding how people are actually tapping their phones to determine which keys are actually being pressed.

Following the acquisition, Pinterest and Fleksy will open source the application. That will give developers a launching point if they also decide they want to figure out new ways for people to input information into their phones.