FastTracker
This is an experimental app for keeping track of intermittent fasts. It supports start/stopping of fasts and keeps track of previous fasts as well.
The state will be remembered with LocalStorage, which means that it is device specific and you cannot yet move info from your phone to your desktop.
It based on React (with hooks) and uses service workers to create a progressive web app.
This is not for every day use yet.
Screenshot
Demo
You can try it out on tonyg.se/projects/fasttracker