# Chain vs Second Brain

The clearest difference is in-app purchases: Second Brain at none against Chain's 3. Second Brain also leads on update cadence (every 2 days vs weekly). Chain's advantage is iOS requirement (15.0 vs 26.0). On price, ads and device support there is nothing between them.

Both are free to download. Chain sells 3 in-app purchases, starting at $2.99 per month. Second Brain asks for nothing beyond the download.

Chain ships an update weekly, Second Brain every 2 days. The most recent releases landed on October 21, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | Chain | Second Brain |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 90.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Weekly | **Every 2 days** |
| Monetization | Freemium | — |
| Size | 21 MB | 26 MB |
| Requires iOS | **15.0** | 26.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Muhammed Talha POLAT](https://appshunter.io/developer/1731811922) | [kim dahye](https://appshunter.io/developer/1868391710) |

## What reviewers say

### Chain

[App page](https://appshunter.io/ios/app/chain-habit-tracker-and-streak/id6478146486)

This app helps you build positive habits and break negative ones through a visual tracking system. Set goals, monitor daily progress, and receive reminders to stay on track. Customize your experience with themes and gain insights into your long-term progress.

**Highlights:** Build unbreakable habit chains, Daily progress tracking with calendar view, Set and achieve personal goals, Routine loop for habit acquisition, Customizable reminders, Motivational quotes and insights, User-friendly interface with themes

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Chain Pro Access - Monthly | $2.99 | per month |
| Chain Pro Access - Annual | $12.99 | per year |
| Chain Pro Access Lifetime | $24.99 | one-time |


### Second Brain

[App page](https://appshunter.io/ios/app/second-brain-ai-note/id6799343264)

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

**In-app purchases:** none


## Frequently asked questions

### Is Chain free?

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

### Is Second Brain free?

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

### Do Chain or Second Brain have ads?

Neither Chain nor Second Brain shows ads.

### Which is updated more often, Chain or Second Brain?

Chain ships an update weekly, and Second Brain every 2 days. Most recently, Chain was updated on October 21, 2026 and Second Brain on October 10, 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.*