Zero is a popular, polished intermittent fasting app — but its advanced features sit behind the Zero Plus subscription, and it asks you to create an account. If you just want a clean fasting timer that's completely free and doesn't ask for sign-up, IF24 is a straightforward alternative.
IF24 vs Zero at a glance
| IF24 | Zero | |
|---|---|---|
| Price | Free (all features) | Free tier + Zero Plus subscription |
| Account required | No | Yes (sign-up) |
| Data collected | None (App Store: “Data Not Collected”) | See its App Store privacy label |
| Metabolic phase estimates (fat burning, ketosis, autophagy) | Yes, free | Some insights behind Zero Plus |
| Schedules | 16:8, 18:6, 20:4, custom | Multiple presets + custom |
| Platform | iPhone (iOS) | iOS, Android |
Why pick IF24
If your priority is a free, private, no-friction fasting timer that shows estimated fat burning, ketosis and autophagy phases based on typical timing, IF24 covers exactly that without a subscription or account. Zero remains a strong choice if you want its broader ecosystem and don't mind the paid tier.
Comparison last updated June 2026 and based on publicly available information; competitor features and pricing may change — check the respective app's official page for the latest. Zero is a trademark of its owner, used here only to identify the app for comparison. IF24 is an independent app and is not affiliated with or endorsed by Zero. Metabolic phases shown by IF24 are estimates based on typical fasting timing, not measurements, and are not medical advice.