Mater is a very simple menubar Pomodoro app. It's written in Electron and there are binaries for Mac, Windows, and Linux.
I've used a bunch of Pomodoro apps in the past and never found found one that hit the sweet spot for simplicity and nice design. When I found myself wanting to learn Electron, I decided to scratch both itches at the same time!
Chronos is a simple and powerful tool that lets you manage your time more efficiently and in a systematic way which ensures maximum productivity. Time management can often prove tricky for some, so using a time management tool like Chronos will help you ease the situation.