24-TET Keys: Microtonal MIDI

24-TET Keys: Microtonal MIDI

Quarter Tones on a Keyboard

5 ratings
3 reviews
Free

Details

  • Released
  • Updated
  • July 14, 2026
  • July 16, 2026

Features

24-TET Keys: Microtonal MIDI screenshot #1 for iPhone
24-TET Keys: Microtonal MIDI screenshot #2 for iPhone
24-TET Keys: Microtonal MIDI screenshot #3 for iPhone
iphone
ipad
🖼️Get Icon
Icons↘︎

About

Explore microtonal music with a virtual keyboard that plays notes between standard semitones. Hear quarter tones instantly, send them as MIDI to your DAW, and discover unique keyboard layouts that morph into each other.

Microtonal keyboard for quarter tones
MIDI output to DAWs
Morphing keyboard layouts
Polyphonic and mono MIDI modes
Visual representation of 24-TET
On-device sound playback
Show original description

What's New in 24

1.2

July 16, 2026

A new isomorphic layout: one move always means the same interval, anywhere on the board. The screen no longer dims while you play.

User reviews

Unique Instrument!

Full disclosure: I am not a fan of quarter-tones — microtonality, yes, but straight quarter-tones just sound out-of-tune to this Westerner. That said, this is a unique instrument! I would love to see an option of switching to Just tuning (which is its own form of microtonality, but designed to be more harmonically pleasing to Western musical traditions), but one cannot downgrade the developer for straying from the intended purpose of an app that generates quarter-tones only! For instrument sounds, you have the option of piano (kind of a honky-tonk sound), synth (sine-wave), and (Hammond-like) organ. You also have several options on how the “keyboard” is laid out. Props to the developer for this option! My only suggestions are: 1) to have a zoomable keyboard (or to allow for two- or three-tiered rows, so one doesn’t have to scroll to get notes out-of-range of the current keyboard position; and 2) Allow for a full piano range (like the 88 keys in a 12-tone setting) — that the top tone as-is goes only to a B is a bummer — at least finish the C scale out to a top C! :-) Conclusion: Definitely get this app! It is innovative, and it works! (I have not tried it in MIDI mode.)
Show more

Very cool.

I enjoyed playing around with this. The only thing I’d change is adding the ability to loop a sequence of keys to build up a track and add a guitar/bass sound option.

How do you import the keys to garageband?

so far I love this app and I have some ideas: can you allow sampling on this keyboard, maybe allow different experiment tunings such as 31 tet and the ability to zoom in and out of the keyboard to make it bigger or smaller?

Next thing, how do you import this to garageband?

Developer apps

FAQ

How do quarter tones work in 24-TET Keys?

Quarter tones divide the semitone in half. While standard 12-TET divides the octave into 12 equal steps, 24-TET divides it into 24, placing a new note exactly between every pair of existing notes.

Can I use 24-TET Keys with my music software?

Yes, 24-TET Keys functions as a compact microtonal MIDI keyboard. It sends MIDI data over CoreMIDI to hosts like GarageBand, Logic, and AUM via USB, network MIDI, or hardware MIDI.

What is 24-TET?

24-TET stands for 24-tone equal temperament, an alternative tuning system that divides the octave into 24 equal steps, with each step being a quarter tone. It's used in modern microtonal and xenharmonic music.

Does 24-TET Keys have ads?

No, 24-TET Keys does not contain advertisements.

What devices is 24-TET Keys available on?

24-TET Keys is available for iPhone and iPad.

How does the morphing keyboard layout work?

The app features experimental keyboard layouts that dynamically transform into one another. You can start with a piano-derived layout and morph into others like a domino, honeycomb, or isomorphic layout.

What is the rating of 24-TET Keys?

24-TET Keys has a high rating of 4.6 stars based on 5 user ratings.

Is 24-TET Keys suitable for beginners?

While the concept of microtonality can be complex, the app's visual morphing layouts and on-device sound playback make it accessible for users to explore quarter tones and experiment with new musical ideas.