I have been using Vora since September 5 to track my fasting. It has some good base analytics if you are into that sort of thing. I set my goal to 16hr but I typically do at least 20. I have ended a couple at 14 for social situations at work, but otherwise, the 20 hour fasts are pretty easy for me now.
Here is a screenshot of the base stats. I paid for premium to support the developer and it has some more graphs but those aren’t all that interesting to me.