the Fitbit mobile app
A clockface with all your current heath stats, with the time & date down the right - the dot line is your battery strength - it gets shorter as battery goes down.
TAP on the right side (time/date) of the screen to see a bigger version of the time & date, plus the battery number (bottom left) AND a very basic stopwatch/counter with three (3) buttons to tap at the top of the screen - start, stop, clear.
The counter will keep running while the screen is off, however it will reset if you open any app. Its maximum value is 59:59, and it will restart at 00:00 after this. It doesn't do hours, or milliseconds - if you want longer than an hour or milliseconds, use the built in stopwatch. Anyway, having the screen on this long, or constantly checking it over the course of multiple hours, will rapidly reduce battery life.
Clock supports 12/24 hr.
Date formats mmdd/ddmm.
Change colour of the time/date on the main screen and the large time (on the second screen)
1.99 no trial