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music21

Free#24 of 38 in Music Notation SoftwareMusic Theory Software

music21: A free, open-source toolkit for structured score analysis and transformation. Ranked #24 of 38 in Music Notation Software by our editors (6.8/10); pricing: Free plan; best for programmatic music analysis and transformation.

6.8/10Editor score

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At a glance

Editor score
6.8 / 10
Pricing
Free plan
Best for
Programmatic music analysis and transformation
Free plan
Yes
Paid from
Free
Deployment
Both
Facts checked
22 Sep 2026

Where it wins
- Structured objects for scores, parts, measures, voices, and notes
- MusicXML and MIDI import and export support
- Analysis modules, corpus access, and fretboard representations
Where it doesn't
- Not a conventional standalone score editor
- Better suited to technically oriented users than traditional notation authors
- Notation output may involve text, graphics, or external software workflows

Our verdict on music21

music21 is an open-source Python toolkit for computer-aided musical analysis and computational musicology. It represents musical material as structured objects, including scores, parts, measures, voices, and notes, giving researchers, educators, developers, and technically oriented musicians a way to manipulate symbolic musical data. MusicXML and MIDI import and export support connects it with common notation and sequencing workflows, while its web, Windows, macOS, Linux, and API availability supports different working environments.

Its strongest fit is computational depth rather than conventional score authoring. The toolkit includes music-theory and computational-analysis modules, musical corpus access and searching, and operations for changing scores and parts, including combining parts into voices. Guitar and other fretboard representations add useful coverage for users working with instrumental or tablature-related material. These capabilities make music21 suitable for repeatable analysis, transformation, education, and research workflows built around structured musical content.

The main trade-off is product shape: music21 is a Python library, not a conventional standalone notation editor. Published workflows include local installation and web execution through Google Colab, while notation output can be text-based, graphical, or passed to external notation software. Choose music21 when programmable manipulation, analysis, corpus access, or format conversion is central. Choose a conventional notation editor instead when the primary need is direct, visual score authoring.

Your product? Our editors can test music21 in depth and publish a review, labelled as paid · from $149/mo →

music21 pricing

Plans Free planFree Free to use — no paid tier required for the core job.

See plans on music21.org

music21 fact sheet

Free plan	Yes
Paid from	Free
Deployment	Both
MusicXML support	Yes
MIDI support	Yes
Parts extraction	Yes
Tablature support	Yes
Collaboration features	Not verified
Deployment	Cloud, Desktop
Platforms	Web, Windows, macOS, Linux
Support	Community, Docs
Pricing	Free plan
Website	music21.org
Facts checked	22 Sep 2026

Alternatives to music21

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Also Ranked In

music21 is ranked in 2 of our directories.

#23Music Theory Software27 tools ranked

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Featured on iTechGuides

music21 is listed in our Music Notation Software directory. Add the badge to your site — it links back to this page.

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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Last updated 7 Oct 2026 · How we research and update