# Nautilus vs Acumen³

The clearest difference is in-app purchases: Acumen³ at none against Nautilus's 3. Acumen³ also leads on iOS requirement (15.1 vs 26.0). Nautilus's advantage is update cadence (fortnightly vs every 15 months). On price, ads and device support there is nothing between them.

Both are free to download. Nautilus sells 3 in-app purchases, starting at $3.99 per month. Acumen³ asks for nothing beyond the download.

Nautilus ships an update fortnightly, Acumen³ every 15 months. The most recent releases landed on November 6, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Nautilus | Acumen³ |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (3.2K ratings)](https://appshunter.io/ios/app/nautilus-web-word-annotate/id1422480068/reviews)** | — |
| Number of ratings | **3.2K** | — |
| Positive reviews | 48.3% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Fortnightly** | Every 15 months |
| Monetization | Freemium | — |
| Size | 502 MB | 30 MB |
| Requires iOS | 26.0 | **15.1** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 17+ | 4+ |
| Developer | [Kairoos Solutions SL](https://appshunter.io/developer/978066434) | [Micromax](https://appshunter.io/developer/1690107784) |

## What reviewers say

### Nautilus

[App page](https://appshunter.io/ios/app/nautilus-web-word-annotate/id1422480068)

This app is a research-focused web browser and writing tool for iPad and iPhone. It allows users to read, annotate web pages and PDFs, and use AI for summarization and content generation. The app also supports document creation and organization, syncing across cloud services.

**Highlights:** Web browsing with research tools, AI-powered page summarization and translation, Direct annotation on web pages and PDFs, Export markup as PDF, Word, or Markdown, Integrated document drafting and organization, Cloud syncing with Dropbox, Google Drive, and iCloud, Lecture and interview recording with transcripts

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Nautilus Unlock All and AI | $3.99 | per month |
| Nautilus Unlock All and AI | $14.99 | per year |
| Nautilus Pro Lifetime | $14.99 | one-time |

**What reviewers like**

- 🚀 Excellent note-taking app
- 📁 Great folder organization
- 🎨 Customizable notebook covers
- 🔍 Useful PDF annotation tools
- 🤖 Impressive AI capabilities

**What reviewers complain about**

- 🐛 Frequent crashes and bugs
- 🔄 Sync and file transfer issues
- 🕰️ Slow performance and lag
- 🔒 Poor customer support
- 💰 Misleading upgrade pricing

**Reported bugs**

- Notes randomly disappearing
- Formatting issues with text and images
- Unreliable audio recording and playback
- Compatibility problems with newer iOS versions
- Inability to transfer files between free and pro versions

**Requested features**

- Handwriting recognition
- Improved eraser and shape tools
- Customizable keyboard and toolbar
- Better integration with cloud storage
- Ability to rotate and resize images


### Acumen³

[App page](https://appshunter.io/ios/app/acumen/id6449690175)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Nautilus free?

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

### Is Acumen³ free?

Acumen³ is free to download, with no in-app purchases.

### Do Nautilus or Acumen³ have ads?

Neither Nautilus nor Acumen³ shows ads.

### Which is updated more often, Nautilus or Acumen³?

Nautilus ships an update fortnightly, and Acumen³ every 15 months. Most recently, Nautilus was updated on November 6, 2026 and Acumen³ on October 30, 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.*