Fr3tLab
Interactive Guitar Fretboard Visualizer — Any Tuning
Been practicing modes on a 7-string in Drop C, and most fretboard visualizers don’t even know a 7-string exists. The ones that do look like they were built in 2009 and haven’t been touched since. Dark theme? Good luck. Extended range? Usually not. Custom tuning beyond EADGBE? Maybe, if you click through six menus and hope.
So I built something. Fr3tLab — a free, browser-based guitar fretboard visualizer that runs any tuning from 4-string bass to 8-string extended, covers 40+ scales, handles chords, arpeggios, progressions, and a chord identifier, all with audio. No install. No login. No ads. It’s a passion project I’m putting out for free — I just wanted everyone who plays to be able to use it. Works right now.
Why I built it
7-string Drop C is B E A D G B E — one step below standard 7-string, where the low B becomes A. Most tools either don’t have a 7-string preset at all, or they have it but won’t let you tune it differently. And almost none of them look right on a dark screen at midnight when you’re actually in the practice room.
Built Fr3tLab in Claude Design as a personal tool that solved my specific problem. After I finished it, figured it was worth putting live — someone else is probably in the same spot. The twenty years of playing guitar post explains more of the context — this is the part of the work where theory and practice are finally connecting for me.
The tool assumes you play real guitars. Not just Stratocasters.
What it does
Five modes. Pick one, set your tuning, and go. Audio is WebAudio — click a fret or hit play and you hear it through your browser, no plugins needed.
40+ scales: Major, Minor, Dorian, Phrygian Dominant, Lydian Dominant, Bebop Dominant, Hungarian Minor, Whole Tone, Diminished — the stuff you actually need. Pick a root, pick a scale, every note lights up. Toggle Degrees mode to color-code by interval (root, 3rd, 5th, 7th, etc.) instead of just notes. Click any fret and the note sounds.
36 chord qualities — major, minor, dominant 7th, maj7, min7, sus2, sus4, add9, 9, 11, 13, diminished, augmented, and more. Shows playable shapes for your current tuning and string count. Hit ▶ to hear a strum. Shapes adjust when you change tuning — no hardcoded EADGBE shapes.
Same chord shapes, played as sweeps — ascending, descending, or both. Each shape highlights the root note separately from the rest of the arpeggio tones so you can see where the pattern anchors. Useful for visualizing how a sweep pattern maps to an actual fretboard position.
12 progressions built in: I-V-vi-IV, 12-bar blues, Pachelbel, Andalusian cadence, jazz ii-V-I, and others. Pick a key, pick major or minor, set the BPM, enable loop, and let it play through while you follow along on your instrument. Fretboard updates in real time as each chord hits.
Tap notes anywhere on the neck and the tool names the chord those intervals form, then lists which scales contain all those notes. Works in whatever tuning you’ve set. Useful for reverse-lookup — “what chord am I accidentally playing?” and “what modes can I solo over this with?”
How to use it
Pull up Fr3tLab at fr3tlab.com in any desktop browser — works on Chrome, Firefox, Safari, Edge. Mobile works too but a real fretboard has 22 frets; it’s cramped on a phone screen. Start with the tuning selector in the top bar: pick your string count, then your tuning. If you’re on a 7-string Drop C, select “7-String” then “Drop C.” The fretboard redraws immediately. Then pick a mode, set a root note and key, and start clicking. If you’re a theory person, musictheory.net is a solid free resource to cross-reference what you’re seeing — understanding why the notes fall where they do makes the tool click faster.
Capo support is in the top bar too — set it and every mode adjusts. Lefty mode flips the neck. No account required, no ads, no paywall. Use it as much as you want.
California metal guitarist — fill-in/session + wedding band
More on the guitar side of things in the more music posts section.
Jesse Moraga · Guitarist · Fresno, CA · jessemoraga.com
Jesse Moraga 
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