This is a personal time tracking app designed and developed by and for myself. More info at my blog and Hacker News.
You're welcome to try it out for yourself by installing an APK from the releases page, but be warned that the app requires Android 10+ and has undergone essentially zero QA! Feel free to open a GitHub issue if you're having problems.
All entries are written to a local TSV file in external storage for easy sync/backup.
I used this project to learn Kotlin and (re)learn Android development before I began work on the Duolingo app, which is now 100% Kotlin!