# PDF AI vs K37 Simple Projects

The clearest difference is ads: K37 Simple Projects at none against PDF AI's shown. K37 Simple Projects also leads on update cadence (every 6 days vs every 6 weeks). PDF AI's advantage is iOS requirement (15.0 vs 17.0). On price, in-app purchases and device support there is nothing between them.

Both are free to download. PDF AI sells 6 in-app purchases, starting at $2.99 per 7 days and K37 Simple Projects sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

PDF AI ships an update every 6 weeks, K37 Simple Projects every 6 days. The most recent releases landed on September 21, 2026 and September 30, 2026 respectively.

## The numbers

| Metric | PDF AI | K37 Simple Projects |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (24 ratings)](https://appshunter.io/ios/app/pdf-ai-reader-and-translator/id6503428926/reviews)** | — |
| Number of ratings | **24** | — |
| Positive reviews | 25.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 6 weeks | **Every 6 days** |
| Monetization | Free with in-app purchases | — |
| Size | 77 MB | 6 MB |
| Requires iOS | **15.0** | 17.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [AvnTech Inc.](https://appshunter.io/developer/1478209663) | [K37 Software LLC](https://appshunter.io/developer/1886297629) |

## What reviewers say

### PDF AI

[App page](https://appshunter.io/ios/app/pdf-ai-reader-and-translator/id6503428926)

This app offers a comprehensive suite of tools for managing PDF documents. It allows users to read, scan, edit, convert, and translate PDFs using integrated AI technology. Streamline your workflow with this all-in-one PDF solution.

**Highlights:** High-quality PDF reader with bookmarking and search, Ultra PDF scanner with auto-cropping, Image to PDF converter, Edit text, images, and sign PDFs, AI-powered PDF document translator, Add annotations, highlights, and stamps

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

**In-app purchases (6)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly | $2.99 | per 7 days |
| Monthly | $5.99 | per month |
| Weekly | $9.99 | per 7 days |
| Yearly | $9.99 | per year |
| Monthly | $19.99 | per month |
| Yearly | $39.99 | per year |


### K37 Simple Projects

[App page](https://appshunter.io/ios/app/k37-simple-projects/id6795298936)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Simple Projects Full | $2.99 | one-time |


## Frequently asked questions

### Is PDF AI free?

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

### Is K37 Simple Projects free?

K37 Simple Projects is free to download, with in-app purchases available.

### Do PDF AI or K37 Simple Projects have ads?

PDF AI shows ads; K37 Simple Projects does not.

### Which is updated more often, PDF AI or K37 Simple Projects?

PDF AI ships an update every 6 weeks, and K37 Simple Projects every 6 days. Most recently, PDF AI was updated on September 21, 2026 and K37 Simple Projects on September 30, 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.*