AnySoftKeyboard is an open source keyboard for Android devices. It has an active community on GitHub and is available for Android 1.5 and up devices, so basically for every device possible. It is a private and fast alternative, weighning just 6.5MB, with over 40 supported languages. You can download the app from Google Play Store or F-Droid. I ran across this app a few weeks back and decided to contribute by designing a new website for them.