# PDF AI vs Lumen

The clearest difference is in-app purchases: Lumen at none against PDF AI's 3. Lumen also leads on ads (none vs shown) and update cadence (every 2 weeks vs every 6 weeks). PDF AI's advantage is device support (3 vs 1) and iOS requirement (15.0 vs 18.0). On price there is nothing between them.

Both are free to download. PDF AI sells 3 in-app purchases, starting at $2.99 per 7 days. Lumen asks for nothing beyond the download.

PDF AI ships an update every 6 weeks, Lumen every 2 weeks. The most recent releases landed on October 16, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | PDF AI | Lumen |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (4 ratings)](https://appshunter.io/ios/app/lumen-knowledge-browser/id6762682475/reviews)** |
| Number of ratings | — | **4** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Every 6 weeks | **Every 2 weeks** |
| Monetization | — | Free |
| Size | 7 MB | 28 MB |
| Requires iOS | **15.0** | 18.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 17+ |
| Developer | [TECH LOGIC HOST](https://appshunter.io/developer/1335938195) | [Daniel Kosukhin](https://appshunter.io/developer/1852657475) |

## What reviewers say

### PDF AI

[App page](https://appshunter.io/ios/app/pdf-ai-chat-summarize-and-ocr/id6758303451)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| PDF Doc Pro Weekly | $2.99 | per 7 days |
| PDF Doc Pro Monthly | $7.99 | per month |
| PDF Doc Pro Yearly | $29.99 | per year |


### Lumen

[App page](https://appshunter.io/ios/app/lumen-knowledge-browser/id6762682475)

This app acts as a browser that remembers what you read, building a personal knowledge base from engaged pages. It allows you to ask questions in plain English about your reading history, with answers generated by an on-device AI. All your data remains private and offline.

**Highlights:** On-device AI knowledge base, Plain English questioning, Automatic content organization, Private and offline browsing, Tracker blocking, Source citation for answers

**In-app purchases:** none


## Frequently asked questions

### Is PDF AI free?

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

### Is Lumen free?

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

### Do PDF AI or Lumen have ads?

PDF AI shows ads; Lumen does not.

### Which is updated more often, PDF AI or Lumen?

PDF AI ships an update every 6 weeks, and Lumen every 2 weeks. Most recently, PDF AI was updated on October 16, 2026 and Lumen on October 14, 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.*