Chordia

Chordia is a free Chrome extension designed to simplify the complex music theory behind the diatonic accordion. This intuitive tool lets users visualize chords, scales, and key arrangements graphically, without needing advanced theoretical knowledge or familiarity with the instrument's irregular keyboard layout. Supported by Diato Trad in Nanterre, France, Chordia enables accordion enthusiasts and musicians to discover and understand treble and bass chords, various scales, and keyboard configurations with ease.

From its first release in 2013, Chordia has evolved by adding features such as treble and bass chord discovery, editing keyboard layouts, scale visualization, and even sound playback. It remains an essential resource for both beginners and advanced players looking to master the diatonic accordion's secrets efficiently and enjoyably.