# PenDrop vs KnowUp

The clearest difference is in-app purchases: PenDrop at none against KnowUp's 2. KnowUp's advantage is update cadence (every 2 days vs every 5 days) and iOS requirement (15.0 vs 17.0). On price, ads and device support there is nothing between them.

Both are free to download. KnowUp sells 2 in-app purchases, starting at $2.99 per month. PenDrop asks for nothing beyond the download.

PenDrop ships an update every 5 days, KnowUp every 2 days. The most recent releases landed on October 12, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | PenDrop | KnowUp |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 5 days | **Every 2 days** |
| Size | 46 MB | 89 MB |
| Requires iOS | 17.0 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [AKIO FURUTSUKA](https://appshunter.io/developer/1869216839) | [Wenfeng Duan](https://appshunter.io/developer/1454244715) |

## What reviewers say

### PenDrop

[App page](https://appshunter.io/ios/app/pendrop/id6757839057)

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

**In-app purchases:** none


### KnowUp

[App page](https://appshunter.io/ios/app/knowup-ai-flashcards-and-study/id6779905080)

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| knowup monthly | $2.99 | per month |
| knowup annual | $24.99 | per year |


## Frequently asked questions

### Is PenDrop free?

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

### Is KnowUp free?

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

### Do PenDrop or KnowUp have ads?

Neither PenDrop nor KnowUp shows ads.

### Which is updated more often, PenDrop or KnowUp?

PenDrop ships an update every 5 days, and KnowUp every 2 days. Most recently, PenDrop was updated on October 12, 2026 and KnowUp on October 3, 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.*