# DiagramAI vs OpenAPI Viewer

The clearest difference is in-app purchases: DiagramAI at none against OpenAPI Viewer's 3. DiagramAI also leads on iOS requirement (15.0 vs 18.1). OpenAPI Viewer's advantage is ads (none vs shown) and update cadence (every 2 weeks vs every 6 months). On price and device support there is nothing between them.

Both are free to download. OpenAPI Viewer sells 3 one-off in-app purchases. DiagramAI asks for nothing beyond the download.

DiagramAI ships an update every 6 months, OpenAPI Viewer every 2 weeks. The most recent releases landed on October 12, 2026 and October 5, 2026 respectively.

## The numbers

| Metric | DiagramAI | OpenAPI Viewer |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 6 months | **Every 2 weeks** |
| Size | 149 MB | 13 MB |
| Requires iOS | **15.0** | 18.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac |
| Age rating | 4+ | 4+ |
| Developer | [Daniel Nowendsztern](https://appshunter.io/developer/1028876626) | [Victor Manuel Puga Ruiz](https://appshunter.io/developer/1648773908) |

## What reviewers say

### DiagramAI

[App page](https://appshunter.io/ios/app/diagramai/id6758946256)

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

**In-app purchases:** none


### OpenAPI Viewer

[App page](https://appshunter.io/ios/app/openapi-viewer/id6761346493)

**Features:** Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Small Tip | $1.99 | one-time |
| Medium Tip | $4.99 | one-time |
| Large Tip | $9.99 | one-time |


## Frequently asked questions

### Is DiagramAI free?

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

### Is OpenAPI Viewer free?

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

### Do DiagramAI or OpenAPI Viewer have ads?

DiagramAI shows ads; OpenAPI Viewer does not.

### Which is updated more often, DiagramAI or OpenAPI Viewer?

DiagramAI ships an update every 6 months, and OpenAPI Viewer every 2 weeks. Most recently, DiagramAI was updated on October 12, 2026 and OpenAPI Viewer on October 5, 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.*