# zen vs Astrarium

The clearest difference is review sentiment: zen at 100% against Astrarium's 50%. zen also leads on in-app purchases (none vs 2) and update cadence (every 5 days vs every 10 days). Astrarium's advantage is price (Free vs $0.99) and device support (4 vs 2). On ads there is nothing between them.

Astrarium is free to download; zen costs $0.99 up front. Astrarium sells 2 in-app purchases, starting at $3.99 per month. zen asks for nothing beyond the download.

zen ships an update every 5 days, Astrarium every 10 days. The most recent releases landed on October 25, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | zen | Astrarium |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Positive reviews | **100.0% of reviews** | 50.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Every 5 days** | Every 10 days |
| Monetization | Paid | **Free** |
| Size | 6 MB | 132 MB |
| Requires iOS | 26.0 | **17.0** |
| Devices | iPhone, iPad | **iPhone, iPad, Mac, Apple Watch** |
| Age rating | 12+ | 4+ |
| Developer | [Taiyo Fujii](https://appshunter.io/developer/1889371389) | [Shinsuke Abe](https://appshunter.io/developer/6790818921) |

## What reviewers say

### zen

[App page](https://appshunter.io/ios/app/zen-babel/id6761398433)

Translate text and documents offline using your device. This app prioritizes privacy by keeping all data local, offering both fast machine translation and AI-powered options. It supports various file formats and image text extraction.

**Highlights:** Offline translation, On-device processing, Text and image translation, Supports various file types, Machine and AI translation options, Side-by-side comparison

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

**In-app purchases:** none


### Astrarium

[App page](https://appshunter.io/ios/app/astrarium/id6795053748)

Explore the cosmos with an offline planetarium and sky atlas. View stars, nebulae, constellations, planets, and more with detailed information and adjustable time settings. Includes augmented reality features and export options.

**Highlights:** Offline sky charting, Detailed star and object catalogs, Adjustable time and location settings, Augmented reality view, Meteor shower calendar, Satellite tracking, PNG/PDF export

**Features:** Apple Watch app, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Astrarium Pro Monthly | $3.99 | per month |
| Astrarium Pro Yearly | $39.99 | per year |


## Frequently asked questions

### Is zen free?

zen costs $0.99, with no in-app purchases.

### Is Astrarium free?

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

### Do zen or Astrarium have ads?

Neither zen nor Astrarium shows ads.

### Which is updated more often, zen or Astrarium?

zen ships an update every 5 days, and Astrarium every 10 days. Most recently, zen was updated on October 25, 2026 and Astrarium on October 24, 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.*