Compare software

FastTrack vs Zero: catalog facts
FastTrack	Zero
Free Free and open source under the MIT licence, with no ads or in-app purchases.	Freemium Free to download, with a paid subscription for additional features.
Android	Android, iOS
No ads, purchases or permissions Shows what the body is doing at each stage of a fast	One-tap fasting timer Meal logging by photo or text description
Android only Not a medical app	Mobile only, no web version Less detailed nutrient tracking than full calorie counters
Downloadable app	Downloadable app
Open source	Closed source
License: MIT	License not stated
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.