music21 vs MusicTheory.net

music21 is a free Python toolkit for computer-aided musicology, used to study music datasets, teach music theory, edit notation, analyze music, generate examples, and compose. It includes a corpus of thousands of encoded works, plus tools for searching that corpus, plotting pitch, and performing advanced analysis such as nPVI. The toolkit works with MIDI and MusicXML and can be extended to handle other formats. Its documentation recommends MuseScore for viewing and editing notation, and describes MusicXML readers including Finale, Sibelius, and Dorico. Optional integrations include LilyPond, Matplotlib, SciPy, PyAudio, and Pygame; music21 can also be used in web-based Jupyter Notebook. It runs on Linux, macOS, and Windows, with web use through Jupyter. The toolkit is BSD-licensed and costs nothing. Some corpus works have separate license restrictions. Users need some familiarity with Python, and music21 works primarily with symbolic music data rather than sound waves; it cannot read notation directly from images or PDFs.

MusicTheory.net is a free, ad-free music theory learning site with animated lessons, practice exercises, and reference tools. Lessons address notation, rhythm, scales, intervals, chords, and chord progressions. Online exercises cover identifying and constructing material on the staff, keyboard, and fretboard, as well as ear training. Calculators handle accidentals, intervals, scales, chords, analysis, and twelve-tone matrices; other tools include a tempo tapper and staff paper generator. Teachers can make permanent links to customized exercises and validate exercise verification codes. Students can create signed Progress Reports with codes teachers can verify. Lessons, exercises, and tools can be embedded in other sites using HTML frames or iframes; the FAQ recommends a minimum size of 600 by 600 pixels. The Tenuto app for iPhone and iPad adds 24 exercises, six calculators, customization, Challenge Mode, and offline use. Theory Lessons is an iPhone and iPad app with 39 animated lessons. The website plan includes all site content at free, with no ads.