# CatTrans vs Building a Second Brain

The clearest difference is in-app purchases: Building a Second Brain at none against CatTrans's 3. CatTrans's advantage is iOS requirement (14.0 vs 16.4). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. CatTrans sells 3 one-off in-app purchases. Building a Second Brain asks for nothing beyond the download.

CatTrans ships an update every 2 months, Building a Second Brain every 4 months. The most recent releases landed on September 28, 2026 and October 13, 2026 respectively.

## The numbers

| Metric | CatTrans | Building a Second Brain |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.7 (12 ratings)](https://appshunter.io/ios/app/building-a-second-brain/id6744942882/reviews)** |
| Number of ratings | — | **12** |
| Positive reviews | — | 50.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 4 months |
| Monetization | — | Free |
| Size | 212 MB | 90 MB |
| Requires iOS | **14.0** | 16.4 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 17+ |
| Developer | [SoundAI Technology Co.,Ltd](https://appshunter.io/developer/1475331895) | [Forte Labs, LLC](https://appshunter.io/developer/1810064260) |

## What reviewers say

### CatTrans

[App page](https://appshunter.io/ios/app/cattrans/id6744315223)

**Features:** macOS Compatibility

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Cat Membership-Week | $1.99 | one-time |
| Cat Membership-Month | $4.99 | one-time |
| Cat Membership-Year | $9.99 | one-time |


### Building a Second Brain

[App page](https://appshunter.io/ios/app/building-a-second-brain/id6744942882)

This app helps you manage information overload and achieve your goals through personal knowledge management. Connect with a community focused on productivity and digital organization for a more peaceful and purposeful life.

**Highlights:** PARA Method Mini-Course, Community Hub, Exclusive event invitations, Notetaking and creativity resources, Gateway to comprehensive courses

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

**In-app purchases:** none


## Frequently asked questions

### Is CatTrans free?

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

### Is Building a Second Brain free?

Building a Second Brain is free to download, with no in-app purchases.

### Do CatTrans or Building a Second Brain have ads?

Neither CatTrans nor Building a Second Brain shows ads.

### Which is updated more often, CatTrans or Building a Second Brain?

CatTrans ships an update every 2 months, and Building a Second Brain every 4 months. Most recently, CatTrans was updated on September 28, 2026 and Building a Second Brain on October 13, 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.*