Contrapunctus vs music21

Contrapunctus is a free web platform for music theory, composition, and counterpoint study. Its real-time editor shows Roman-numeral and chord analysis while users write, and identifies part-writing errors and non-chord tones. Compositions can use multiple voices, major, minor, or modal contexts, and sampled-instrument playback. The platform includes an interactive edition of Fux’s Gradus ad Parnassum, with species-counterpoint lessons, an AI tutor, and English and Latin text. Community members can create and solve exercises, share solutions, vote, and earn points toward a 15-rank ladder. Educators can create classes, assign lessons, review submissions, and track scores and class averages in a gradebook. Accounts use email or Google, with projects and activity synchronized across devices. Plain and compressed MusicXML can be imported, but MusicXML or MIDI export is not yet shipped. Some imported details may be simplified or dropped, and tutor free-form questions are limited to 25 per account per rolling hour.

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.