SwiftKey, one of the most popular third-party keyboards for Android(s GOOG) phones, is now a free app. Previously, the keyboard replacement cost $4, but version 5.0, which is now available on Google Play, will instead offer several keyboard themes as in-app purchases.

In addition to the new keyboard themes — most of which cost $1 — version 5.0 improves the SwiftKey word prediction engine and adds a few new handy features. The biggest change? SwiftKey now supports emoji, and can even predict what emoji you were going to type based on which ones you most often use with specific words and phrases. There’s also a new optional number row that can be added to the top of your keyboard.

SwiftKey is known for its focus on natural language processing and machine learning: it was one of the first mobile keyboards to offer predictive text suggestions based on previously written emails and texts, a feature…