A free interactive fretboard tool for guitar, bass, mandolin, banjo, and ukulele. Makes scales, modes, and chord theory visible and audible — not just theoretical.
How to use it
Select your instrument, tuning, root key, and scale or mode. The fretboard lights up with color-coded notes. Click any dot to hear it. Use Ascending and Descending to hear the full scale in order. Use ◀ ▶ to slide the fret window up and down the neck.
Color coding
🔴 Red — root note
🟢 Teal green — pentatonic tones
🟡 Gold — added modal tones
🟣 Purple — blues ♭5
Chords
Each scale shows its diatonic chords with Roman numeral functions. Click any chord to hear it strummed or arpeggiated and see its fretboard voicing.
Scales that fit this chord
When you click a chord, a panel appears listing every scale in Fretcrawler that contains that chord. Click any scale chip to jump straight to it — the fretboard updates instantly. This is how you escape the pentatonic box: see exactly which scales open up over each chord you're playing.
Scales included
Minor & Major Pentatonic · Blues · Dorian · Aeolian · Phrygian · Mixolydian · Lydian · Ionian · Harmonic Minor · Melodic Minor · Lydian Dominant · Whole Tone · Diminished (Half-Whole)
What you can learn
Each scale includes a plain-English description of its character, a signature trick — the one move that defines its sound — and classic example songs. Use it to learn where notes live, train your ear, and understand why certain scales feel the way they do over certain chords.
The climber?
He's just here for the ride. No note bends required.
