tonaljs/tonal

A music theory library for Javascript

TypeScript

4,253

1,043 commits

updated Sep 29, 2026

See the code

README

tonal

npm version

tonal is a music theory library. Contains functions to manipulate tonal elements of music (note, intervals, chords, scales, modes, keys). It deals with abstractions (not actual music or sound).

tonal is implemented in Typescript and published as a collection of Javascript npm packages.

It uses a functional programming style: all functions are pure, there is no data mutation, and entities are represented by data structures instead of objects.

Example

import { Chord, Interval, Note, Scale } from "tonal";

Note.midi("C4"); // => 60
Note.freq("a4"); // => 440
Note.accidentals("c#2"); // => '#'
Note.transpose("C4", "5P"); // => "G4"
Interval.semitones("5P"); // => 7
Interval.distance("C4", "G4"); // => "5P"

// Scales
Scale.get("C major").notes; // => ["C", "D", "E", "F", "G", "A", "B"];
[1, 3, 5, 7].map(Scale.degrees("C major")); // => ["C", "E", "G", "B"]

Chord.get("Cmaj7").name; // => "C major seventh"

// Chord inversions
const triad = Chord.degrees("Cm");
[1, 2, 3].map(triad); // => ["C", "Eb", "G"];
[2, 3, 1].map(triad); // => ["Eb", "G", "C"];
[3, 1, 2].map(triad); // => ["G", "C", "Eb"];

Install

Install all packages at once:

npm install --save tonal

You can read CHANGELOG here.

Usage

Tonal is compatible with both ES5 and ES6 modules, and browser.

ES6 import:

import { Note, Scale } from "tonal";

ES5 require:

const { Note, Scale } = require("tonal");

Browser

You can use the browser version from jsdelivr CDN directly in your html:

<script src="https://cdn.jsdelivr.net/npm/tonal/browser/tonal.min.js"></script>
<script>
  console.log(Tonal.Key.minorKey("Ab"));
</script>

Or if you prefer, grab the minified browser ready version from the repository.

Bundle size

tonal includes all published modules.

Although the final bundle it is small, you can reduce bundle sizes even more by installing the modules individually, and importing only the functions you need.

Note that individual modules are prefixed with @tonaljs/. For example:

npm i @tonaljs/note
import { transpose } from "@tonaljs/note";
transpose("A4", "P5");

Documentation

Visit the documentation site or the README.md of each module 👇

Notes and intervals

Scales and chords

Voicings

Keys, chord progressions

Time, rhythm

Utilities

Contributing

Read contributing document. To contribute open a PR and ensure:

  • If is a music theory change (like the name of a scale) link to reliable references.
  • If is a new feature, add documentation: changes to README of the affected module(s) are expected.
  • Ad tests: changes to the test.ts file of the affected module(s) are expected.
  • All tests are green

Inspiration

This library takes inspiration from other music theory libraries:

Projects using tonal

Showcase of projects that are using Tonal:

Thank you all!

Add your project here by editing this file

License

MIT License

chord-progression
chords
functional
interval
javascript
key-signatures
music
music-theory
scale
transpose
typescript

tonaljs/tonal

A music theory library for Javascript

TypeScript

4,253

1,043 commits

updated Sep 29, 2026

See the code

README

tonal

npm version

tonal is a music theory library. Contains functions to manipulate tonal elements of music (note, intervals, chords, scales, modes, keys). It deals with abstractions (not actual music or sound).

tonal is implemented in Typescript and published as a collection of Javascript npm packages.

It uses a functional programming style: all functions are pure, there is no data mutation, and entities are represented by data structures instead of objects.

Example

import { Chord, Interval, Note, Scale } from "tonal";

Note.midi("C4"); // => 60
Note.freq("a4"); // => 440
Note.accidentals("c#2"); // => '#'
Note.transpose("C4", "5P"); // => "G4"
Interval.semitones("5P"); // => 7
Interval.distance("C4", "G4"); // => "5P"

// Scales
Scale.get("C major").notes; // => ["C", "D", "E", "F", "G", "A", "B"];
[1, 3, 5, 7].map(Scale.degrees("C major")); // => ["C", "E", "G", "B"]

Chord.get("Cmaj7").name; // => "C major seventh"

// Chord inversions
const triad = Chord.degrees("Cm");
[1, 2, 3].map(triad); // => ["C", "Eb", "G"];
[2, 3, 1].map(triad); // => ["Eb", "G", "C"];
[3, 1, 2].map(triad); // => ["G", "C", "Eb"];

Install

Install all packages at once:

npm install --save tonal

You can read CHANGELOG here.

Usage

Tonal is compatible with both ES5 and ES6 modules, and browser.

ES6 import:

import { Note, Scale } from "tonal";

ES5 require:

const { Note, Scale } = require("tonal");

Browser

You can use the browser version from jsdelivr CDN directly in your html:

<script src="https://cdn.jsdelivr.net/npm/tonal/browser/tonal.min.js"></script>
<script>
  console.log(Tonal.Key.minorKey("Ab"));
</script>

Or if you prefer, grab the minified browser ready version from the repository.

Bundle size

tonal includes all published modules.

Although the final bundle it is small, you can reduce bundle sizes even more by installing the modules individually, and importing only the functions you need.

Note that individual modules are prefixed with @tonaljs/. For example:

npm i @tonaljs/note
import { transpose } from "@tonaljs/note";
transpose("A4", "P5");

Documentation

Visit the documentation site or the README.md of each module 👇

Notes and intervals

Scales and chords

Voicings

Keys, chord progressions

Time, rhythm

Utilities

Contributing

Read contributing document. To contribute open a PR and ensure:

  • If is a music theory change (like the name of a scale) link to reliable references.
  • If is a new feature, add documentation: changes to README of the affected module(s) are expected.
  • Ad tests: changes to the test.ts file of the affected module(s) are expected.
  • All tests are green

Inspiration

This library takes inspiration from other music theory libraries:

Projects using tonal

Showcase of projects that are using Tonal:

Thank you all!

Add your project here by editing this file

License

MIT License

chord-progression
chords
functional
interval
javascript
key-signatures
music
music-theory
scale
transpose
typescript

Project health

Overall

4.8/10

Maintained

10/10

Code review

6/10
OpenSSF Scorecard

Latest release

6.5.0 · Sep 28, 2026

Releases this year

2

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(top 24 of 48)

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331 followers · starred May 2023

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218 followers · starred Apr 2024

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1,021 followers · starred Nov 2020

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4,534 followers · starred Apr 2024