# KeyPad MIDI Controller vs Harmonic 639

The clearest difference is in-app purchases: KeyPad MIDI Controller at none against Harmonic 639's 3. KeyPad MIDI Controller also leads on ads (none vs shown) and update cadence (every 4 days vs monthly). On price, rating and device support there is nothing between them.

Both are free to download. Harmonic 639 sells 3 in-app purchases, starting at $9.99 per month. KeyPad MIDI Controller asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 4.9 for KeyPad MIDI Controller against 5.0 for Harmonic 639. That said, the two scores are not equally well evidenced: KeyPad MIDI Controller has 16 ratings behind it against 1, so its average is the more settled of the two.

KeyPad MIDI Controller ships an update every 4 days, Harmonic 639 monthly. Both last shipped on October 24, 2026.

## The numbers

| Metric | KeyPad MIDI Controller | Harmonic 639 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.9 (16 ratings)](https://appshunter.io/ios/app/keypad-midi-controller/id6758680165/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/harmonic-639/id6761851668/reviews)** |
| Number of ratings | **16** | 1 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 4 days** | Monthly |
| Monetization | Free | — |
| Size | 14 MB | 70 MB |
| Requires iOS | **15.0** | 17.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [DiscoDSP LLC](https://appshunter.io/developer/1465262828) | [Robin Webber](https://appshunter.io/developer/1891777775) |

## What reviewers say

### KeyPad MIDI Controller

[App page](https://appshunter.io/ios/app/keypad-midi-controller/id6758680165)

Transform your device into a professional MIDI controller with touch-optimized piano keys, drum pads, and performance controls. It supports SFZ, SF2, WAV, and M4A samples, and can control iOS apps, hardware synths, and Mac software wirelessly or wired.

**Highlights:** Touch-optimized piano keyboard, 9-pad drum grid, XY performance pad, Built-in sound engine (SF2, SFZ, WAV, M4A), AUv3 plugin support, Network MIDI for Mac control, Aftertouch and MPE expression

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

**In-app purchases:** none


### Harmonic 639

[App page](https://appshunter.io/ios/app/harmonic-639/id6761851668)

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Harmonic 639 Monthly | $9.99 | per month |
| Harmonic 639 Quarterly | $19.99 | per 3 months |
| Harmonic 639 Annual | $69.99 | per year |


## Frequently asked questions

### Is KeyPad MIDI Controller free?

KeyPad MIDI Controller is free to download, with no in-app purchases.

### Is Harmonic 639 free?

Harmonic 639 is free to download, with in-app purchases available.

### Which has better reviews, KeyPad MIDI Controller or Harmonic 639?

Harmonic 639 is rated higher. KeyPad MIDI Controller averages 4.9 out of 5 from 16 ratings, while Harmonic 639 averages 5.0 from 1 ratings.

### Do KeyPad MIDI Controller or Harmonic 639 have ads?

Harmonic 639 shows ads; KeyPad MIDI Controller does not.

### Which is updated more often, KeyPad MIDI Controller or Harmonic 639?

KeyPad MIDI Controller ships an update every 4 days, and Harmonic 639 monthly. Most recently, KeyPad MIDI Controller was updated on October 24, 2026 and Harmonic 639 on October 24, 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.*