TimeLeft - TimeLeft is a versatile desktop utility - it can be used as a countdown clock, reminder, clock...
TClock Light - TClock allows you to modify the clock on the taskbar in Windows.
Dial - Quick & beautiful macOS timer.
T-Clock Redux - T-Clock Redux in an enhanced fork of Stoic Joker's T-Clock 2010 with ISO week number support...
ChirpyTime - ChirpyTime: Timer / Alarm Clock / Clock app for iPhone / iPod Touch
DS Clock - Keep your time synchronized with Atomic Time servers, using customizable digital desktop clock with westminster chimes.