# AstroFITS vs Zenith Annotation

The clearest difference is update cadence: Zenith Annotation at daily against AstroFITS's monthly. Zenith Annotation also leads on iOS requirement (15.0 vs 17.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. AstroFITS sells 1 in-app purchase, starting at $0.99 per year and Zenith Annotation sells 2 in-app purchases, starting at $24.99 per year. Whichever you choose, the download price is not the number that matters.

AstroFITS ships an update monthly, Zenith Annotation daily. The most recent releases landed on October 8, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | AstroFITS | Zenith Annotation |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[2.0 (1 ratings)](https://appshunter.io/ios/app/astrofits/id6756322104/reviews)** | — |
| Number of ratings | **1** | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Monthly | **Daily** |
| Monetization | Free with in-app purchases | — |
| Size | 61 MB | 47 MB |
| Requires iOS | 17.0 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [yong chong loh](https://appshunter.io/developer/393466709) | [Eduardo Martinez Gomez](https://appshunter.io/developer/6790600757) |

## What reviewers say

### AstroFITS

[App page](https://appshunter.io/ios/app/astrofits/id6756322104)

This app allows users to quickly open and view FITS files on iOS devices using GPU acceleration. It features automatic image stretching and supports various color formats and bit depths, making astronomical image analysis more accessible.

**Highlights:** Open FITS files quickly on iOS, GPU accelerated image processing, Automatic image stretching, Supports RGB and gray color, Handles multiple BITPIX formats, Save adjusted images to Photos

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Yearly Subscription | $0.99 | per year |


### Zenith Annotation

[App page](https://appshunter.io/ios/app/zenith-annotation/id6816010913)

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Annotation Studio with Trial | $24.99 | per year |
| Annotation Studio Annual | $24.99 | per year |


## Frequently asked questions

### Is AstroFITS free?

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

### Is Zenith Annotation free?

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

### Do AstroFITS or Zenith Annotation have ads?

Neither AstroFITS nor Zenith Annotation shows ads.

### Which is updated more often, AstroFITS or Zenith Annotation?

AstroFITS ships an update monthly, and Zenith Annotation daily. Most recently, AstroFITS was updated on October 8, 2026 and Zenith Annotation on October 6, 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.*