# Second Brain vs Lucid

The clearest difference is in-app purchases: Lucid at none against Second Brain's 1. Lucid also leads on update cadence (every 3 days vs every 3 months). Second Brain's advantage is device support (3 vs 1) and iOS requirement (15.0 vs 17.0). On price and ads there is nothing between them.

Both are free to download. Second Brain sells 1 one-off in-app purchase. Lucid asks for nothing beyond the download.

Second Brain ships an update every 3 months, Lucid every 3 days. The most recent releases landed on October 1, 2026 and October 5, 2026 respectively.

## The numbers

| Metric | Second Brain | Lucid |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 3 days** |
| Size | 25 MB | 2 MB |
| Requires iOS | **15.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Selahattin Bozat](https://appshunter.io/developer/1895293163) | [Goo wong Kwon](https://appshunter.io/developer/1895637047) |

## What reviewers say

### Second Brain

[App page](https://appshunter.io/ios/app/second-brain-notes-and-knowledge/id6775839727)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Second Brain Premium | $9.99 | one-time |


### Lucid

[App page](https://appshunter.io/ios/app/lucid-second-brain/id6777908024)

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

**In-app purchases:** none


## Frequently asked questions

### Is Second Brain free?

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

### Is Lucid free?

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

### Do Second Brain or Lucid have ads?

Neither Second Brain nor Lucid shows ads.

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

Second Brain ships an update every 3 months, and Lucid every 3 days. Most recently, Second Brain was updated on October 1, 2026 and Lucid on October 5, 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.*