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 free to fast with and doesn't ask for sign-up, IF24 is a straightforward alternative. IF24 Pro is an optional one-time purchase for advanced extras; nothing you need to run a fast is behind it.
IF24 vs Zero at a glance
| IF24 | Zero | |
|---|---|---|
| Price | Free; IF24 Pro optional (one-time, no subscription) | 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 | 14:10, 16:8, 18:6, 20:4 free; custom length with Pro | 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.
IF24 is free to download; IF24 Pro is an optional one-time purchase for advanced extras. Comparison last updated August 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.