# Siddha vs 21 Days

The clearest difference is in-app purchases: Siddha at none against 21 Days's 4. Siddha also leads on update cadence (weekly vs every 3 weeks). 21 Days's advantage is iOS requirement (15.0 vs 18.2). On price, ads and device support there is nothing between them.

Both are free to download. 21 Days sells 4 in-app purchases, starting at $0.99 per month. Siddha asks for nothing beyond the download.

Siddha ships an update weekly, 21 Days every 3 weeks. The most recent releases landed on November 5, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Siddha | 21 Days |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Weekly** | Every 3 weeks |
| Size | 21 MB | 46 MB |
| Requires iOS | 18.2 | **15.0** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Srinath Vangala](https://appshunter.io/developer/1806796010) | [iLoma Technology](https://appshunter.io/developer/1463653289) |

## What reviewers say

### Siddha

[App page](https://appshunter.io/ios/app/siddha/id6745690040)

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

**In-app purchases:** none


### 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 Siddha free?

Siddha is free to download, with no in-app purchases.

### Is 21 Days free?

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

### Do Siddha or 21 Days have ads?

Neither Siddha nor 21 Days shows ads.

### Which is updated more often, Siddha or 21 Days?

Siddha ships an update weekly, and 21 Days every 3 weeks. Most recently, Siddha was updated on November 5, 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.*