# js vs ProbabilityPlayer

The clearest difference is in-app purchases: js at none against ProbabilityPlayer's 1. js also leads on iOS requirement (13.0 vs 18.0). ProbabilityPlayer's advantage is update cadence (monthly vs every 2 months). On price, ads and device support there is nothing between them.

Both are free to download. ProbabilityPlayer sells 1 one-off in-app purchase. js asks for nothing beyond the download.

js ships an update every 2 months, ProbabilityPlayer monthly. The most recent releases landed on September 14, 2026 and August 27, 2026 respectively.

## The numbers

| Metric | js | ProbabilityPlayer |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 months | **Monthly** |
| Monetization | — | Free with in-app purchases |
| Size | 1 MB | 9 MB |
| Requires iOS | **13.0** | 18.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 9+ | 4+ |
| Developer | [Hiroyuki Nakano](https://appshunter.io/developer/1091174971) | [Motonari Hibi](https://appshunter.io/developer/386737172) |

## What reviewers say

### js

[App page](https://appshunter.io/ios/app/js-star/id1382126067)

**Features:** macOS Compatibility

**In-app purchases:** none


### ProbabilityPlayer

[App page](https://appshunter.io/ios/app/probabilityplayer/id6737689746)

Practice probability problems for the Kyotsu Test, a common Japanese university entrance exam. This app focuses on mathematical probability questions and includes diagrams to aid understanding. It is designed to help students prepare for this specific academic assessment.

**Highlights:** Probability problem practice, Kyotsu Test focus, Mathematical probability, Diagrams included, University entrance exam prep

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium | $1.99 | one-time |


## Frequently asked questions

### Is js free?

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

### Is ProbabilityPlayer free?

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

### Do js or ProbabilityPlayer have ads?

Neither js nor ProbabilityPlayer shows ads.

### Which is updated more often, js or ProbabilityPlayer?

js ships an update every 2 months, and ProbabilityPlayer monthly. Most recently, js was updated on September 14, 2026 and ProbabilityPlayer on August 27, 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.*