Music notation software is clunky and often desktop-only, making collaboration and sharing cumbersome. A web-based editor would solve this, enabling musicians to compose and edit scores directly in the browser.
Focus on features like real-time collaboration, version control, and seamless export/import formats. Educators and composers are the primary users, willing to pay for streamlined workflows.
The smallest version could be a basic notation editor with export to PDF and MIDI. The biggest risk is competing with established players like Sibelius or MuseScore.