Empyreal Keys

Musicians, learners, and curious minds needed a sleek, ad-free pocket piano app that offered an elegant, responsive experience without the clutter and paywalls of traditional apps. It needed to feel like a real instrument, complete with accurate soundfont-based playback, multi-touch support, and helpful practice aids that are always ready to play.

The core design principle was musicality and instant readiness. While building the piano experience, I realized existing Flutter packages couldn't handle the low-latency audio rendering and professional sheet music display I envisioned. Instead of compromising, I built and open-sourced two foundational libraries from scratch: flutter_midi_16kb for lightweight, offline TinySoundFont-based MIDI playback, and flutter_music_notation for rendering professional, SMuFL-compliant Western music notation.

Achieving zero-latency multi-touch support and realistic audio playback required bypassing standard audio plugins, which led to engineering a custom synthesizer integration (flutter_midi_16kb). Furthermore, rendering mathematically accurate sheet music (clefs, 15 key signatures, dynamic barlines) meant building a complete modular layout and rendering engine (flutter_music_notation) capable of 60fps playback with real-time note highlighting.

Empyreal Keys successfully launched as a highly capable, low-storage-friendly pocket piano featuring adjustable key ranges, built-in recorders, and chord modes. By solving my own complex technical hurdles, I not only delivered a premium ad-free app but also contributed two robust, open-source audio and notation libraries back to the global Flutter developer ecosystem.