# 21DaysOfChange vs Formy

The clearest difference is ads: 21DaysOfChange at none against Formy's shown. 21DaysOfChange also leads on iOS requirement (16.4 vs 26.0). Formy's advantage is update cadence (weekly vs every 9 months). On price, in-app purchases and device support there is nothing between them.

Both are free to download. 21DaysOfChange sells 4 in-app purchases, starting at $5.99 per month and Formy sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

21DaysOfChange ships an update every 9 months, Formy weekly. The most recent releases landed on September 18, 2026 and September 6, 2026 respectively.

## The numbers

| Metric | 21DaysOfChange | Formy |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 9 months | **Weekly** |
| Size | 59 MB | 12 MB |
| Requires iOS | **16.4** | 26.0 |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Hong Son Vu](https://appshunter.io/developer/1767993431) | [Koki Teraoka](https://appshunter.io/developer/1865584437) |

## What reviewers say

### 21DaysOfChange

[App page](https://appshunter.io/ios/app/21daysofchange/id6677019535)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 21DaysOfChange Monthly Premium | $5.99 | per month |
| 21DaysOfChange Monthly Business | $17.99 | per month |
| 21DaysOfChange Yearly Premium | $71.99 | per year |
| 21DaysOfChange Yearly Business | $214.99 | per year |


### Formy

[App page](https://appshunter.io/ios/app/formy-simple-habit-tracker/id6757252796)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Formy Pro | $1.99 | one-time |


## Frequently asked questions

### Is 21DaysOfChange free?

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

### Is Formy free?

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

### Do 21DaysOfChange or Formy have ads?

Formy shows ads; 21DaysOfChange does not.

### Which is updated more often, 21DaysOfChange or Formy?

21DaysOfChange ships an update every 9 months, and Formy weekly. Most recently, 21DaysOfChange was updated on September 18, 2026 and Formy on September 6, 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.*