# Intermittent Fasting Tracker vs 21 Days

The clearest difference is iOS requirement: 21 Days at 15.0 against Intermittent Fasting Tracker's 17.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Intermittent Fasting Tracker sells 17 in-app purchases, starting at $0.99 per month and 21 Days sells 4 in-app purchases, starting at $0.99 per month. Whichever you choose, the download price is not the number that matters.

Intermittent Fasting Tracker ships an update every 2 weeks, 21 Days every 3 weeks. The most recent releases landed on November 1, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Intermittent Fasting Tracker | 21 Days |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.9 (52K ratings)](https://appshunter.io/ios/app/intermittent-fasting-tracker/id6448909309/reviews)** | — |
| Number of ratings | **52K** | — |
| Positive reviews | 96.9% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 2 weeks** | Every 3 weeks |
| Monetization | Free with in-app purchases | — |
| Size | 94 MB | 46 MB |
| Requires iOS | 17.0 | **15.0** |
| Devices | iPhone, Apple Watch | iPhone, iPod |
| Age rating | 12+ | 4+ |
| Developer | [Kai Oelfke](https://appshunter.io/developer/644779478) | [iLoma Technology](https://appshunter.io/developer/1463653289) |

## What reviewers say

### Intermittent Fasting Tracker

[App page](https://appshunter.io/ios/app/intermittent-fasting-tracker/id6448909309)

This app offers a straightforward and private way to track intermittent fasting. It supports iPhone and Apple Watch, providing essential features like widgets, notifications, and progress charts without any advertisements. Ideal for both beginners and experienced fasters, it focuses on a simple user interface to support health and wellness goals.

**Highlights:** Interactive Widgets, Notifications, Streaks & Badges, Charts & Trends, Fasting Zones, iCloud Sync, Dark Mode

**Features:** Apple Watch app

**In-app purchases (17)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Fasty Monthly Donation | $0.99 | per month |
| Fasty Basic Monthly | $0.99 | per month |
| Fasty Monthly Donation | $1.99 | per month |
| Fasty Basic Monthly | $1.99 | per month |
| Fasty Monthly Donation | $2.99 | per month |
| Fasty Basic Yearly | $4.99 | per year |
| Fasty Basic Yearly | $6.69 | per year |
| Fasty Pro Monthly | $6.99 | per month |
| Fasty Pro Yearly | $19.99 | per year |
| One Time Donation | $4.99 | one-time |
| Fasty Basic One Time | $9.99 | one-time |
| One Time Donation | $9.99 | one-time |
| One Time Donation | $14.99 | one-time |
| One Time Donation | $24.99 | one-time |
| One Time Donation | $34.99 | one-time |
| Fasty Pro One Time | $49.99 | one-time |
| One Time Donation | $49.99 | one-time |

**What reviewers like**

- 👍 Simple and easy to use
- 🚀 Straightforward fasting tracking
- 🔒 No ads or subscriptions
- 💡 Customizable fasting times
- 👍 Clean and intuitive interface

**What reviewers complain about**

- 🐛 Occasional issues with time tracking
- 💡 Desire for more customization options
- 💡 Request for monthly/yearly fasting view
- 💡 Interest in adding notes or logging features

**Reported bugs**

- Overlapping fasting/eating windows reported
- Inconsistencies in fasting time calculations

**Requested features**

- Ability to schedule and set reminders for fasts
- Option to manually log ketosis levels
- Export or share fasting data
- More detailed fasting stage information


### 21 Days

[App page](https://appshunter.io/ios/app/21-days-habit-tracker/id6751798974)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Monthly | $0.99 | per month |
| Ultra Pro Monthly | $0.99 | per month |
| Pro Yearly | $4.99 | per year |
| Ultra Pro Yearly | $9.99 | per year |


## Frequently asked questions

### Is Intermittent Fasting Tracker free?

Intermittent Fasting Tracker is free to download, with in-app purchases available.

### Is 21 Days free?

21 Days is free to download, with in-app purchases available.

### Do Intermittent Fasting Tracker or 21 Days have ads?

Neither Intermittent Fasting Tracker nor 21 Days shows ads.

### Which is updated more often, Intermittent Fasting Tracker or 21 Days?

Intermittent Fasting Tracker ships an update every 2 weeks, and 21 Days every 3 weeks. Most recently, Intermittent Fasting Tracker was updated on November 1, 2026 and 21 Days on October 30, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*