Chord Tool

📖 Tool Introduction

The Chord Tool is a free online music-theory reference designed for learners and creators, turning abstract harmony into something you can both see and hear. It ships with the four foundation chords that appear again and again in popular, classical and jazz music: the major triad built from the root, major third and perfect fifth, the minor triad built from the root, minor third and perfect fifth, the dominant seventh chord built from the root, major third, perfect fifth and minor seventh, and the diminished triad built from the root, minor third and diminished fifth. To use it, simply tap any one of the twelve piano keys to choose a root note, then select one chord type from the cards. The interface immediately lists every chord tone: the note name such as E4, its MIDI number, and the precise frequency calculated with equal temperament anchored at A4 equals 440Hz. When you press the audition button, several triangle-wave oscillators sound at once, wrapped in a smooth attack and release envelope so you can hear the colour of the chord without audible clicks. The whole tool runs completely offline: no audio samples are downloaded, no network calls are made, and it opens instantly on both phones and laptops, making it a reliable companion for ear training, harmony classes, and arranging practice whenever an exact spelling or reference pitch is needed. Because every note is synthesized from its mathematical frequency rather than played from a recording, there is no waiting for samples to load and no privacy concern about music files being shared anywhere. Songwriters can test how a new chord progression sounds before writing it down, teachers can project the tool on a classroom screen while explaining intervals, and hobbyists can finally tell the difference between a minor third and a diminished fifth purely by listening.

✨ Key Features

• Twelve roots: every semitone from C to B, white and black keys clearly shown
• Four chord types: major, minor, dominant 7th and diminished, with exact intervals
• Chord-tone table: note name, MIDI number and decimal-precise frequency side by side
• Live audition: multiple oscillators sound together with a smooth envelope
• One-tap copy: chord tones and frequencies copy into notes or notation software
• Fully offline: no samples, no network, instant on any device

📝 How to Use

1. Tap a key in the piano row to choose a root, white for naturals, dark for sharps
2. Choose major, minor, dominant 7th or diminished from the chord cards
3. Read the chord-tone table below to learn each note name and frequency
4. Press the audition button and listen for the colour difference
5. Press copy to keep the chord spelling in your own notes

⚠️ Notes

• Octave reference: chords are voiced in the C4 octave for audition, transposition does not matter
• Simplified timbre: the audition uses triangle waves, meant for interval recognition, not real instruments
• Tuning difference: in equal temperament the ratio of two semitones is the twelfth root of two, slightly different from just intonation
• Browser policy: the audio engine starts only after the first tap, which is normal
• Volume safety: simultaneous notes may add up in loudness, keep the level moderate