# Image Converter vs Calistra Viewer

The clearest difference is rating: Calistra Viewer at 5.0 against Image Converter's 4.3. Calistra Viewer also leads on review sentiment (100% vs 88%). Image Converter's advantage is in-app purchases (none vs 1) and iOS requirement (15.1 vs 26.0). On price, ratings volume, update cadence and ads there is nothing between them.

Both are free to download. Calistra Viewer sells 1 one-off in-app purchase. Image Converter asks for nothing beyond the download.

Calistra Viewer holds the better App Store score, 5.0 against 4.3. Both are backed by a comparable volume of ratings — 11 and 4 respectively. Written reviews point the same way: 88% of Image Converter's written reviews are positive against 100% of Calistra Viewer's.

Image Converter ships an update every 3 days, Calistra Viewer every 6 days. Both last shipped on October 31, 2026.

## The numbers

| Metric | Image Converter | Calistra Viewer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.3 (11 ratings)](https://appshunter.io/ios/app/image-converter-batch-resize/id6758528251/reviews) | **[5.0 (4 ratings)](https://appshunter.io/ios/app/calistra-viewer/id6758898157/reviews)** |
| Number of ratings | **11** | 4 |
| Positive reviews | 87.5% of reviews | **100.0% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Every 3 days** | Every 6 days |
| Monetization | **Free** | Free with in-app purchases |
| Size | 39 MB | 345 MB |
| Requires iOS | **15.1** | 26.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Yanchen Zhao](https://appshunter.io/developer/1866053547) | [CHANCELLOR G KREMER](https://appshunter.io/developer/1875360256) |

## What reviewers say

### Image Converter

[App page](https://appshunter.io/ios/app/image-converter-batch-resize/id6758528251)

Easily convert, compress, and resize images in batches with over 9 supported formats. Transform photos into PDFs or optimize them for social media. All processing is done locally on your device for maximum privacy.

**Highlights:** Batch format conversion (JPG, PNG, AVIF, HEIC, etc.), Smart image compression (up to 90% space saving), Social media image resizing presets, Photo to PDF creation, 100% local offline processing, Support for 9+ professional formats

**Features:** macOS Compatibility

**In-app purchases:** none


### Calistra Viewer

[App page](https://appshunter.io/ios/app/calistra-viewer/id6758898157)

This application allows engineers, machinists, and designers to view and inspect complex 3D CAD models on iOS devices. It supports a wide range of file formats and offers tools for measurement, material assignment, and weight calculation, all while operating fully offline.

**Highlights:** Supports STEP, IGES, STL, OBJ, glTF, GLB, PLY, VRML, BREP formats, Precise measurement of dimensions, angles, and lengths, Material assignment and weight calculation, Wireframe, shaded, and edge display modes, Fully offline operation, no account or internet needed, Apple Pencil support with hover previews

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Upgrade | $6.99 | one-time |


## Frequently asked questions

### Is Image Converter free?

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

### Is Calistra Viewer free?

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

### Which has better reviews, Image Converter or Calistra Viewer?

Calistra Viewer is rated higher. Image Converter averages 4.3 out of 5 from 11 ratings, while Calistra Viewer averages 5.0 from 4 ratings.

### Do Image Converter or Calistra Viewer have ads?

Neither Image Converter nor Calistra Viewer shows ads.

### Which is updated more often, Image Converter or Calistra Viewer?

Image Converter ships an update every 3 days, and Calistra Viewer every 6 days. Most recently, Image Converter was updated on October 31, 2026 and Calistra Viewer on October 31, 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.*