# 恒等式 vs MindMark

The clearest difference is in-app purchases: 恒等式 at none against MindMark's 2. 恒等式 also leads on device support (3 vs 1) and iOS requirement (13.0 vs 16.0). On price, update cadence and ads there is nothing between them.

Both are free to download. MindMark sells 2 in-app purchases, starting at $2.99 per year. 恒等式 asks for nothing beyond the download.

恒等式 ships an update fortnightly, MindMark every 2 weeks. Both last shipped on October 30, 2026.

## The numbers

| Metric | 恒等式 | MindMark |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Fortnightly | **Every 2 weeks** |
| Size | 91 MB | 8 MB |
| Requires iOS | **13.0** | 16.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Keshun Waterproof Technologies Co.,Ltd](https://appshunter.io/developer/1615344877) | [琦 刘](https://appshunter.io/developer/1729736385) |

## What reviewers say

### 恒等式

[App page](https://appshunter.io/ios/app/id6447490134)

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

**In-app purchases:** none


### MindMark

[App page](https://appshunter.io/ios/app/mindmark/id6478474978)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| VIP Subscription (1 year) | $2.99 | per year |
| Lifetime VIP | $4.99 | one-time |


## Frequently asked questions

### Is 恒等式 free?

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

### Is MindMark free?

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

### Do 恒等式 or MindMark have ads?

Neither 恒等式 nor MindMark shows ads.

### Which is updated more often, 恒等式 or MindMark?

恒等式 ships an update fortnightly, and MindMark every 2 weeks. Most recently, 恒等式 was updated on October 30, 2026 and MindMark on October 30, 2026.

---

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