# Stack｜自己投資アプリ vs Predy

The clearest difference is in-app purchases: Stack｜自己投資アプリ at none against Predy's 3. Stack｜自己投資アプリ also leads on ads (none vs shown). Predy's advantage is update cadence (every 3 days vs every 10 days). On price, device support and iOS requirement there is nothing between them.

Both are free to download. Predy sells 3 in-app purchases, starting at $4.39 per month. Stack｜自己投資アプリ asks for nothing beyond the download.

Stack｜自己投資アプリ ships an update every 10 days, Predy every 3 days. The most recent releases landed on September 28, 2026 and September 20, 2026 respectively.

## The numbers

| Metric | Stack｜自己投資アプリ | Predy |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/predy-study-trackerpomodoro/id6749900495/reviews)** |
| Number of ratings | — | **1** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 10 days | **Every 3 days** |
| Monetization | — | Free with in-app purchases |
| Size | 41 MB | 339 MB |
| Requires iOS | 17.0 | 17.0 |
| Devices | iPhone, iPad | **iPhone, iPad, Mac** |
| Age rating | 17+ | 4+ |
| Developer | [Nagato Kadoya](https://appshunter.io/developer/1575311338) | [GO SHIMIZU](https://appshunter.io/developer/1767583096) |

## What reviewers say

### Stack｜自己投資アプリ

[App page](https://appshunter.io/ios/app/stack/id6745755185)

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

**In-app purchases:** none


### Predy

[App page](https://appshunter.io/ios/app/predy-study-trackerpomodoro/id6749900495)

This app helps you overcome procrastination and build consistent work habits. It focuses on making starting easy, keeping motivation high, and visualizing your progress. Designed for those who struggle with task management, it turns effort into visible achievement.

**Highlights:** Project-based task management, Work tracking with timers and Pomodoro, StudyWithMe focus mode, AutoPilot for easy task initiation, Streak bonuses and productivity rankings, Progress analytics and prediction training, Goal estimation and feedback

**Features:** Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Predy Premium | $4.39 | per month |
| Predy Premium | $36.49 | per year |
| Predy | $53.99 | one-time |


## Frequently asked questions

### Is Stack｜自己投資アプリ free?

Stack｜自己投資アプリ is free to download, with no in-app purchases.

### Is Predy free?

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

### Do Stack｜自己投資アプリ or Predy have ads?

Predy shows ads; Stack｜自己投資アプリ does not.

### Which is updated more often, Stack｜自己投資アプリ or Predy?

Stack｜自己投資アプリ ships an update every 10 days, and Predy every 3 days. Most recently, Stack｜自己投資アプリ was updated on September 28, 2026 and Predy on September 20, 2026.

---

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