Trainer Stopwatch – Android App for Coaches

An Android stopwatch app for coaches. I wrote it in 2018, when I was racing and needed someone to time me at training. Without any promotion it has over five thousand downloads on Google Play and a 4.8 ★ rating. People kept emailing me ideas for improvements, I just never had the time for them. In 2026 I rewrote it from scratch with the help of AI and released a new version.

The app times several athletes, lanes or intervals at once. Each stopwatch can be named and switching between them takes a single tap. Laps are tagged with colour marks and your own labels, such as Sprint and Rest, and results can be shown as lap times or as cumulative split times. A session is saved to a history grouped by day, results can be shared as text and exported to CSV and Excel. The stopwatches can also be controlled with the volume keys, play a sound on start, stop and lap, and show a notification while running in the background. Light and dark theme, English and Czech. No ads, no sign-up, works offline and the data never leaves the phone.