Music theory tools that spell it right
Most chord sites store a lookup table and hand you F♯ major as "Gb Bb Db". This one does the actual interval arithmetic — so you get F♯ A♯ C♯, and the vii° of F♯ major is E♯dim, exactly as written on the page.
Why the spelling matters
A♯ and B♭ sound identical, but they are not interchangeable on paper. In B major the third is D♯; writing it as E♭ makes the key signature nonsense and the sheet music unreadable. This site builds every chord and scale from real interval arithmetic — letter first, then the accidental needed to hit the right pitch — which is why it can spell G♯ harmonic minor with its F𝄪 instead of quietly turning it into G.
Does the audio need a plugin?
No. Notes are synthesised with the Web Audio API built into your browser. Nothing is downloaded and nothing is uploaded. The first click on a page starts the audio engine — browsers require a user gesture before they allow sound.
Where do the guitar shapes come from?
They are searched, not stored. For each chord the tool walks every fret up to the 12th on all six strings, keeps only the combinations that contain exactly the chord's notes, throws out anything unplayable (a stretch of four frets or more, or a muted string in the middle), then ranks what is left by how easy it is to play and whether the root is in the bass. That is why it also finds shapes for chords no chord chart bothers to include.
Is A440 fixed?
No — the tuning reference is adjustable on the Intervals page if you play with an ensemble at 442, or want historical pitch.
🎹 Chord Builder
Pick a root and a chord type. Everything below is derived, not looked up.
🪜 Scale Explorer
Fifteen scales and modes, spelled correctly on any root.
🔑 Chords in a Key
The chords that belong to a key, with the roman numerals used to talk about them.
🎼 Progression Generator
Common progressions written out in your key — click any chord to hear it, or play the whole thing.
🎯 Circle of Fifths
Click any key on the wheel to see its signature, its relative minor and its chords.
↔️ Transposer
Paste a chord progression and move it to another key.
🎸 Guitar Voicing Finder
Shapes searched from the fretboard — including chords the chord charts skip.
📐 Interval Calculator
Name the distance between two notes, or transpose a note by an interval.
Between two notes
Transpose a note
👂 Ear Trainer
Listen, then name what you heard. Your score is kept for this session.
⏱️ Metronome
Clicks are scheduled ahead on the audio clock, so the beat does not drift.