# RSI STAR vs Sumbi

The clearest difference is in-app purchases: RSI STAR at none against Sumbi's 3. RSI STAR also leads on device support (3 vs 1) and iOS requirement (12.0 vs 16.4). Sumbi's advantage is update cadence (weekly vs every 2 months). On price and ads there is nothing between them.

Both are free to download. Sumbi sells 3 one-off in-app purchases. RSI STAR asks for nothing beyond the download.

RSI STAR ships an update every 2 months, Sumbi weekly. The most recent releases landed on November 3, 2026 and November 6, 2026 respectively.

## The numbers

| Metric | RSI STAR | Sumbi |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/sumbi-study-focus-timer/id6802502926/reviews)** |
| Number of ratings | — | **1** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 months | **Weekly** |
| Monetization | — | Free |
| Size | 38 MB | 94 MB |
| Requires iOS | **12.0** | 16.4 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Akkadu (Beijing) Technology Co., Ltd.](https://appshunter.io/developer/1644872272) | [나이스데이](https://appshunter.io/developer/1751418356) |

## What reviewers say

### RSI STAR

[App page](https://appshunter.io/ios/app/rsi-star/id1644872270)

**Features:** macOS Compatibility

**In-app purchases:** none


### Sumbi

[App page](https://appshunter.io/ios/app/sumbi-study-focus-timer/id6802502926)

This app encourages users to spend less time on their phones by gamifying digital detox. Users engage in timed "dives" away from their devices, earning virtual sea creatures based on their focus duration. It offers a peaceful, non-punitive approach to building healthier digital habits.

**Highlights:** Timed phone-free dives, Unlock virtual sea creatures, Personalized ocean environment, Buddy dive feature, Night sea creatures, Diary-like dive log

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Shallow Sea Creature | $0.99 | one-time |
| Deep Sea Creature | $1.99 | one-time |
| Abyssal Creature | $2.99 | one-time |


## Frequently asked questions

### Is RSI STAR free?

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

### Is Sumbi free?

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

### Do RSI STAR or Sumbi have ads?

Neither RSI STAR nor Sumbi shows ads.

### Which is updated more often, RSI STAR or Sumbi?

RSI STAR ships an update every 2 months, and Sumbi weekly. Most recently, RSI STAR was updated on November 3, 2026 and Sumbi on November 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.*