About Harmodex

Harmodex is a free music reference built to make chords, scales and music-theory concepts visual, practical and interactive.

The website brings together the notes in each chord or scale, intervals, theoretical context, common uses, harmonic relationships, interactive diagrams and sound playback for different instruments.

What you can do on Harmodex

• Look up chords and scales in English and Spanish.
• Explore piano, guitar, ukulele and mandolin.
• See the notes and intervals that make up each chord or scale.
• Listen to chords, arpeggios and scales directly in your browser.
• See the exact key, string or fret position being played in real time.
• Learn about inversions, harmonic relationships, sound, context and musical uses.
• Move between related keys, chord families, scales and instruments.

How the sound works

Harmodex does not need to store a separate MP3 file for every chord or scale. Interactive audio is generated in the browser from the corresponding notes and pitches. Different instruments use distinct playback behaviour to make the reference more useful for learning and comparison.

Musical information and accuracy

Harmodex is designed as a reference and learning tool. We aim to keep notation, intervals, tunings and theoretical relationships accurate, including appropriate enharmonic spelling where relevant.

Music theory can use different naming, fingering, voicing and interpretation conventions depending on context, instrument, musical tradition or teaching method. As a result, the same musical structure may have more than one valid representation.

An evergreen music library

Harmodex is not a news website. Its goal is to work as a long-term music reference: the relationships between notes, intervals, chords and scales do not depend on current events and remain useful whenever you need them.