CASE STUDY: Six Guitar Theory Tools on One Interactive Fretboard
We built a free tool for guitarists that works out scales, chords, and positions from the rules of music theory. Try it at fretmonster.app.
→ The Challenge
Guitar theory is taught through static charts. One chart shows one scale, in one key, in one position, so a player ends up memorizing hundreds of separate pictures.
Pain Points
- Charts Multiply Without End: Every key, mode, and position needs its own diagram, so the material grows faster than anyone can study it.
- No Way to Ask Backwards: A chart goes from a name to a shape. Nothing goes from the notes under a player’s fingers back to the name of the chord or scale.
- One Fretboard, Taught as Separate Systems: Scales, chords, triads, and positions are the same notes in the same places, but they are taught as unrelated topics, so the connection stays hidden.
→ Our Solution
We built FretMonster, a browser application that computes the fretboard from theory rules instead of drawing it chart by chart, so every view works in every key.
We Built
- A Theory Engine in Place of a Chart Library: Scales, triads, and positions are calculated from interval rules at the moment they are requested. That is why each tool works across all 12 keys, every mode, and both major and minor.
- Explorable Views of the Whole Neck: Any scale across the full neck, by position, or in three-note-per-string patterns. A chord dictionary with open, barre, and CAGED fingerings. Triad inversions across every set of strings, and all five CAGED shapes of a chord color-coded up the neck.
- Two-Way Identification: A player taps notes on the fretboard and the tool names the chord they built, including slash chords and alternate readings, or identifies the scale those notes form.
- Free and Public: The tool is live at fretmonster.app for anyone to use, with no account to create and nothing to install.
Why We Built It
“There are a MILLION guitar courses out there. I haven’t found a single app that gives me this much practical visual theory and utility in one place. So I built one.”
– Michael Trezza, CEO Lithyem
Interactive Fretboard Tools
Scales across the whole neck
Tap notes and it names the chord
Tap notes and it names the scale
The chord dictionary
5
CAGED Shapes Mapped Across the Neck
→ The same chord is shown in all five shapes, so players see how the positions connect.
12
Keys Covered by Every Tool
→ Because the fretboard is computed, each tool works in every key, every mode, and both major and minor.
6
Tools on One Page
→ Scales, chords, triads, identification, note names, and the CAGED system share one fretboard and one set of rules.
3
Ways to View Any Scale
→ Across the full neck, by position, or in three-note-per-string patterns.
