# Lambda vs RhythmKey

The clearest difference is price: RhythmKey at Free against Lambda's $2.99. RhythmKey also leads on update cadence (every 3 days vs every 54 months). Lambda's advantage is rating (5.0 vs 2.0) and in-app purchases (none vs 3). On ratings volume, ads, device support and iOS requirement there is nothing between them.

RhythmKey is free to download; Lambda costs $2.99 up front. RhythmKey sells 3 one-off in-app purchases. Lambda asks for nothing beyond the download.

Lambda holds the better App Store score, 5.0 against 2.0. Both are backed by a comparable volume of ratings — 1 and 1 respectively.

Lambda ships an update every 54 months, RhythmKey every 3 days. The most recent releases landed on October 4, 2026 and October 5, 2026 respectively.

## The numbers

| Metric | Lambda | RhythmKey |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/lambda/id434581690/reviews)** | [2.0 (1 ratings)](https://appshunter.io/ios/app/rhythmkey-find-bpm-and-keys/id6739074803/reviews) |
| Number of ratings | 1 | 1 |
| Positive reviews | 80.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 54 months | **Every 3 days** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 6 MB | 1 MB |
| Requires iOS | 15.6 | **15.0** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [dgApps](https://appshunter.io/developer/357488432) | [Robin Nap](https://appshunter.io/developer/1782983860) |

## What reviewers say

### Lambda

[App page](https://appshunter.io/ios/app/lambda/id434581690)

This app helps musicians and sound engineers convert between musical notes, frequencies, and wavelengths. It features a dynamic fader, built-in oscillator, and frequency tracker with waveform display. Customize tuning standards and speed of sound for precise audio analysis.

**Highlights:** Convert notes, frequencies, wavelengths, Dynamic fader for real-time adjustment, Built-in oscillator with waveform, Frequency tracker with waveform, Customizable tuning standards, Adjustable speed of sound, Share data via standard methods

**In-app purchases:** none


### RhythmKey

[App page](https://appshunter.io/ios/app/rhythmkey-find-bpm-and-keys/id6739074803)

Easily determine the tempo and musical key of your audio tracks. This tool offers precise BPM detection through tapping or manual adjustment, along with key matching capabilities to enhance your music production and DJ sets.

**Highlights:** Tap to find BPM, Manual tempo adjustment, Half-time and double-time tempo display, Major scale key matching, Intuitive interface

**Features:** macOS Compatibility

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Fresh Croissant | $1.99 | one-time |
| Croissant & Jam | $3.99 | one-time |
| Deluxe Breakfast | $5.99 | one-time |


## Frequently asked questions

### Is Lambda free?

Lambda costs $2.99, with no in-app purchases.

### Is RhythmKey free?

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

### Which has better reviews, Lambda or RhythmKey?

Lambda is rated higher. Lambda averages 5.0 out of 5 from 1 ratings, while RhythmKey averages 2.0 from 1 ratings.

### Do Lambda or RhythmKey have ads?

Neither Lambda nor RhythmKey shows ads.

### Which is updated more often, Lambda or RhythmKey?

Lambda ships an update every 54 months, and RhythmKey every 3 days. Most recently, Lambda was updated on October 4, 2026 and RhythmKey on October 5, 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.*