Comparison

Lambda vs RhythmKey

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Lambda

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
Read full description

Musicians and Sound Engineers. Musical Notes and Frequencies and Wavelengths. Now there's an app from dgApps to convert between them all. The app features a sliding fader to dynamically change frequency, wavelength and musical note, with locks to step through standard third octave frequencies or whole musical notes. There's a built in oscillator so you can hear the frequency, and a frequency tracker so the app can tell you the frequency. Both the oscillator and the frequency tracker display the audio waveform. A settings section allows for different tuning standards, and variations in the speed of sound. Lambda can also receive calculated Speed of Sound in Air values from another dgApps app, Cair. Lambda is now a universal app, equally at home on an iPhone as on an iPad. In Split Mode on an iPad device, side by side with Cair, the calculated Speed of Sound in Air is passed in real time to the Lambda app. Lambda allows you to share frequency/wavelength/note data via all the usual sharing methods.

About

RhythmKey

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
Read full description

RhythmKey is your go-to app for tempo and key matching, whether you’re a musician, DJ, or producer. With a sleek and intuitive interface, you can: • Tap for Tempo: Quickly find the BPM by tapping along with your track. • Manual Tempo Adjustment: Swipe over the tempo to increase or decrease it with precision. • Half-Time and Double-Time: Instantly see tempo variations for flexible creativity. • Key Matching: Discover matching keys within the Major Scale to elevate your compositions and transitions. Designed for ease of use and accuracy, RhythmKey helps you stay in sync and in tune with your music.

Screenshots

Lambda4 screens
RhythmKey4 screens

Verdict

The call

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.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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.

Scorecard5 real differences · 5 level
Lambda versus RhythmKey: the parameters behind the verdict, then further details
ParameterLambdaRhythmKey
Price$2.99Free — better
Rating5.0 (1 ratings) — better2.0 (1 ratings)
Positive reviews80.0% of reviews—
Number of ratings11
Update frequencyEvery 54 monthsEvery 3 days — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree with in-app purchases — better
DevicesiPhone, iPad, iPod — betteriPhone, iPod
Requires iOS15.615.0 — better
Further details — not scored
Size6 MB1 MB
Age rating4+4+
DeveloperdgAppsRobin Nap

Customer experience

Lambda

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews5 reviews
Positive80.0%
Neutral0.0%
Negative20.0%

RhythmKey

All ratings1 ratings
Positive0.0%
Neutral0.0%
Negative100.0%

In-app purchases

None

Lambda

No in-app purchases

3 purchases

RhythmKey

One-time3
  • Fresh Croissant$1.99
  • Croissant & Jam$3.99
  • Deluxe Breakfast$5.99

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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