The price wasn't disclosed and all of CrossInstall's 70 staff will join Twitter.
CrossInstall came to prominence in the mid-2010s when the first wave of mobile game developers started using its smarts to create simple interactive adverts to promote their games.
Mobile Strike dev MZ was a particularly heavy early user, but since then the likes of Jam City and Glu have also used the technology, which enables developers to push their ads through Google Ads, Facebook and Snap.
More generally, Twitter has been looking to boost its performance advertising business and it’s expected CrossInstall will be integrated with Twitter's existing in-app monetisation platform MoPub.
In a statement, CrossInstall commented: "The combination of CrossInstall and Twitter will highlight Twitter's commitment to performance advertising.
"Together, we'll be working to expand Twitter's reach into all areas of app install and performance advertising while increasing the value that MoPub offers to mobile app developers. Together, we have a clear mission."