# PDF Reader vs Harmonix OTC

The clearest difference is ads: Harmonix OTC at none against PDF Reader's shown. Harmonix OTC also leads on update cadence (every 2 days vs every 115 months) and iOS requirement (11.0 vs 14.0). On price, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

PDF Reader ships an update every 115 months, Harmonix OTC every 2 days. The most recent releases landed on October 10, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | PDF Reader | Harmonix OTC |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | Yes | **No** |
| Update frequency | Every 115 months | **Every 2 days** |
| Size | 9 MB | 128 MB |
| Requires iOS | 14.0 | **11.0** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Aishvarya Sadasivam](https://appshunter.io/developer/1062048241) | [Huizhou Jinghao Medical Technology Co.,Ltd.](https://appshunter.io/developer/1543340471) |

## What reviewers say

### PDF Reader

[App page](https://appshunter.io/ios/app/pdf-reader-sign/id1084660270)

**Features:** macOS Compatibility

**In-app purchases:** none


### Harmonix OTC

[App page](https://appshunter.io/ios/app/harmonix-otc/id6756475067)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is PDF Reader free?

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

### Is Harmonix OTC free?

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

### Do PDF Reader or Harmonix OTC have ads?

PDF Reader shows ads; Harmonix OTC does not.

### Which is updated more often, PDF Reader or Harmonix OTC?

PDF Reader ships an update every 115 months, and Harmonix OTC every 2 days. Most recently, PDF Reader was updated on October 10, 2026 and Harmonix OTC on October 6, 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.*