# CatalogueMessier vs Rock Identifier

The clearest difference is price: Rock Identifier at Free against CatalogueMessier's $0.99. Rock Identifier also leads on update cadence (every 8 days vs every 3 weeks). CatalogueMessier's advantage is in-app purchases (none vs 3). On ads, device support and iOS requirement there is nothing between them.

Rock Identifier is free to download; CatalogueMessier costs $0.99 up front. Rock Identifier sells 3 in-app purchases, starting at $4.99 per 7 days. CatalogueMessier asks for nothing beyond the download.

CatalogueMessier ships an update every 3 weeks, Rock Identifier every 8 days. The most recent releases landed on November 5, 2026 and November 11, 2026 respectively.

## The numbers

| Metric | CatalogueMessier | Rock Identifier |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 3 weeks | **Every 8 days** |
| Monetization | Paid | — |
| Size | 9 MB | 27 MB |
| Requires iOS | 17.0 | 17.0 |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Laurent DURLIAT](https://appshunter.io/developer/1796721727) | [Ebubekir Sezer](https://appshunter.io/developer/1648044330) |

## What reviewers say

### CatalogueMessier

[App page](https://appshunter.io/ios/app/cataloguemessier/id6747948514)

Explore the Messier, NGC, and Caldwell astronomical catalogs. Log your observations with photos, filter celestial objects by type, and track your progress with detailed statistics. Export your data for further analysis.

**Highlights:** View Messier, NGC, and Caldwell catalogs, Add observation photos, Filter objects by category, Track observation progress, Export observation data, Multi-language support

**In-app purchases:** none


### Rock Identifier

[App page](https://appshunter.io/ios/app/rock-identifier-rocco/id6801804012)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly | $4.99 | per 7 days |
| Monthly | $9.99 | per month |
| Yearly | $39.99 | per year |


## Frequently asked questions

### Is CatalogueMessier free?

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

### Is Rock Identifier free?

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

### Do CatalogueMessier or Rock Identifier have ads?

Neither CatalogueMessier nor Rock Identifier shows ads.

### Which is updated more often, CatalogueMessier or Rock Identifier?

CatalogueMessier ships an update every 3 weeks, and Rock Identifier every 8 days. Most recently, CatalogueMessier was updated on November 5, 2026 and Rock Identifier on November 11, 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.*