Hey All! 👋

I'm excited to share Openthesia, a MIDI visualizer and practice tool I’ve been building as an open-source alternative to similar applications.

🎹 What is Openthesia?
It’s a desktop app that lets you visualize MIDI files, play from your keyboard, or learn pieces interactively. You can customize everything, from note colors and hand separation to playback direction and speed.

⭐ Features

Fully customizable: change background and note blocks color, turn on notes glowing effect
Midi playback: play and visualize midi files at different speeds, tempo and notes direction
Learning mode: wait for the right key input before going to the next note
Play mode: visualize midi input realtime and record it to export it as a midi file
Hands separation: differentiate between left and right hand with colors
SoundFonts support: built-in and external sounds support through .sf2 files

New in the Supporter Edition (huge thank you if you grab it ❤️)

Built-in video recording: capture high-quality video of your MIDI playbacks and performances and save them directly. Perfect for sharing on platforms like YouTube.
VST plugins support: use your favorite instruments and audio effects directly inside Openthesia! Customize your sound with synths, pianos, reverbs, and more.

The core app is totally free and open-source on GitHub. But if you find it useful or want to support indie dev work, the Supporter Edition is a great way to help.

Thanks for checking it out!

Alex