music21

music21 is a Python toolkit for studying, teaching, analyzing, and composing with symbolic music. It suits people comfortable working in Python who want to ask questions of encoded scores or build music into code; its analytical range comes with a clear boundary around audio and scanned notation.

Overview

At its best, music21 connects a large body of encoded music with tools for searching and analysis. Musicologists can explore patterns across works, while teachers and composers can generate examples or manipulate notation programmatically. It is a flexible toolkit rather than a finished score editor, so users should expect to work through code and other music software as needed.

The toolkit is BSD-licensed and free. Its corpus has its own terms: some works or directories restrict commercial use or carry other conditions. Check the license for the material you plan to use, especially when building a commercial project.

Key features

Corpus research and analysis

Corpus search, pitch plotting, and advanced functions such as nPVI give users several ways to examine encoded works. The included corpus of thousands of pieces makes it practical to investigate music beyond a single score, and to turn findings into teaching examples or compositional material. These tools depend on symbolic data, so they do not analyze sound waves from recordings.

Formats and notation workflows

music21 works with MIDI and MusicXML, supports part extraction and tablature, and can be extended to other formats. For reading or editing scores, its documentation points users to MuseScore and describes support for MusicXML readers such as Finale, Sibelius, and Dorico. That is a useful bridge to established notation applications, though it means score editing is not the toolkit’s central strength.

Optional integrations

Optional connections to LilyPond, Matplotlib, SciPy, PyAudio, and Pygame support tasks including score rendering, plotting, audio searching, recording, and realtime MIDI. Jupyter Notebook can also be used for web-based work. This breadth gives technically minded users room to assemble a workflow around a particular project, but makes Python familiarity a real prerequisite rather than a bonus.

Pricing

music21: free. The BSD-licensed toolkit has no paid tier to unlock its core use. Community mailing-list help is available, and paid consulting is offered at project-dependent rates. Corpus works may have separate restrictions, so free software does not make every included score available for every use.

Platforms

music21 supports Linux, macOS, Windows, and web use, including through Jupyter Notebook. It is available for both self-managed and hosted deployment. The configuration assistant asks whether the toolkit may access the Internet, but Internet access is not required.

Who it's for

Musicologists, programmers, composers, performers, teachers, and music enthusiasts can all find uses for music21, provided they have some familiarity with Python. It is especially well suited to research and instruction involving encoded scores, and to composition workflows that benefit from programmatic analysis or example generation. Choose a notation application for direct score editing, and an audio or optical music recognition tool if your starting point is a recording, image, or PDF.

Pros and cons

• Pros: A free, BSD-licensed toolkit combines a corpus of thousands of works with search and analysis functions, supporting research and teaching without a software fee.
• Pros: MIDI and MusicXML support, part extraction, tablature, and optional integrations give Python users several ways to connect analysis with notation and other workflows.
• Cons: Some Python familiarity is needed, which makes it a poor fit for someone seeking a ready-to-use graphical music application.
• Cons: It works primarily with symbolic musical data; it cannot read notation directly from images or PDFs or work directly from audio waveforms.
• Cons: Corpus licenses vary, so users must check individual works before commercial use or other restricted applications.

Alternatives

For broader options, browse Music Theory Software or Music notation software.

For structured practice rather than Python-based score analysis, Harmonia offers a free independent-practice plan and a Classroom Connect option priced at 20.95 for up to four weeks; its free plan omits advanced analyzing and feedback features. note-noodle may suit ear-training practice: its free tier allows 10 sessions a day and three personal Play Along uploads per month, with the first four lessons available without an account.

ChordIQ is another freemium option for readers comparing music-learning apps. Music Master offers free website lessons and practice questions without an account, while Musicca makes all content free and lets a free account unlock it and remove ads. For exercise-based study, MyMusicTheory has more than 100 free exercises, and Study Music Theory offers a full course and eight trainers without ads or paywalls. Teoria provides free website content with optional sign-in.

Verdict

Choose music21 if you know some Python and want a free, capable toolkit for exploring, teaching, or creating with encoded music. Its corpus and analysis tools are the strongest reasons to use it. Look elsewhere when the job starts with recorded audio or scanned notation, or when you need a dedicated graphical score editor.