GrvMkr
Online grid notation & beat making tool
GrvMkr is a free, browser-based tool for creating percussion grid notation and playing it back. It was built as a replacement for an old Windows-only app called MangoDrum — so that community musicians can create, share and hear rhythm patterns on any device.
You can lay out beats on a grid, adjust tempo, and share your grooves via URL. No account required, no install needed.
Built with Svelte and DaisyUI, it’s been iterated on over several weeks across four dev-log posts — adding persistence, triplet support, mobile PWA support and groove sharing.