Cost: Free
The Life Intermittent Fasting app allows you to track your progress on any fasting schedule, since you're able to set the start and end time and goals for how long you want to fast for. There's a clock that counts the minutes and hours fasted, so a quick glance can make you feel proud that you've fasted that long.
This app also keeps track of how many total hours you've fasted and your total number of fasts, and also monitors your weekly fasting progress, including how many hours you've been in ketosis. If you have fasting friends who use this app, you can fast together, and the support could help you stick with it.