# DI9FLOW vs AstroStacker

The clearest difference is in-app purchases: DI9FLOW at none against AstroStacker's 3. DI9FLOW also leads on iOS requirement (15.6 vs 17.0). AstroStacker's advantage is update cadence (every 2 weeks vs monthly). On price, ads and device support there is nothing between them.

Both are free to download. AstroStacker sells 3 in-app purchases, starting at $12.99 per month. DI9FLOW asks for nothing beyond the download.

DI9FLOW ships an update monthly, AstroStacker every 2 weeks. The most recent releases landed on November 6, 2026 and November 12, 2026 respectively.

## The numbers

| Metric | DI9FLOW | AstroStacker |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[1.1 (7 ratings)](https://appshunter.io/ios/app/astrostacker-stack-the-sky/id6753679598/reviews)** |
| Number of ratings | — | **7** |
| Positive reviews | — | 0.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Monthly | **Every 2 weeks** |
| Monetization | — | Freemium |
| Size | 14 MB | 17 MB |
| Requires iOS | **15.6** | 17.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [芝青 蔡](https://appshunter.io/developer/1326079618) | [Ahmed Al-Mahmud](https://appshunter.io/developer/1844352476) |

## What reviewers say

### DI9FLOW

[App page](https://appshunter.io/ios/app/di9flow/id1352779642)

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

**In-app purchases:** none


### AstroStacker

[App page](https://appshunter.io/ios/app/astrostacker-stack-the-sky/id6753679598)

Enhance your night sky photos by stacking multiple exposures into a single, detailed image. This app automatically aligns stars, reduces noise, and offers tools to refine your astrophotography results directly on your iPhone or iPad.

**Highlights:** Stack multiple night sky photos, Automatic star alignment, Noise reduction for clearer images, Advanced editing tools, Support for calibration frames (Pro), On-device processing

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| AstroStacker app | $12.99 | per month |
| AstroStacker app | $99.99 | per year |
| AstroStacker app | $219.00 | one-time |


## Frequently asked questions

### Is DI9FLOW free?

DI9FLOW is free to download, with no in-app purchases.

### Is AstroStacker free?

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

### Do DI9FLOW or AstroStacker have ads?

Neither DI9FLOW nor AstroStacker shows ads.

### Which is updated more often, DI9FLOW or AstroStacker?

DI9FLOW ships an update monthly, and AstroStacker every 2 weeks. Most recently, DI9FLOW was updated on November 6, 2026 and AstroStacker on November 12, 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.*