Cavaquinho Hero
Today I’m releasing my longest-running WIP pet project. I started working on this music student toolkit during the 2020 pandemic, right before my daughter was born. It’s been my “try random ideas” project for years, and I never really cared about publishing it.
It started as a small vanilla JS library to generate scales and chords for cavaquinho (and other fretted instruments). Then I slapped on a very ugly React UI. From there it grew: harmonic fields, chord formation, a move to Next.js, and eventually a full rewrite in TypeScript. It’s now hosted for free on GitHub, available in English and Portuguese, with all translations handled on the frontend. I also decided to open source it, even though I don’t expect to actively maintain it unless a really good idea shows up. A lot of the recent rewriting was done with help from an AI assistant, which still surprises me.
The project is called Cavaquinho Hero. It generates major and minor scales, harmonic fields, chord formations, and a table of common preparation chords (II–V, SubV, Prep. Dim.) for each degree.
I’ve also added a fretboard visualizer to show how to find chords on the instrument (still in beta). All the shapes represent the same chord, but some are more common than others — I may add a way to reorder and save favorites.
Give it a try: