THUNDERFRET
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Guitar // theory engine

Know it.
Then slay it.

Learn how music actually works on guitar — the theory, the fretboard, the ear — then walk on stage and let it rip. Study to solo, all in one tool.

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Theory ♦Practice ♦Slay ♦Pro hears you play ♦Guitar ♦Fretboard ♦Compose ♦No signup ♦Free ♦Theory ♦Practice ♦Slay ♦Pro hears you play ♦Guitar ♦Fretboard ♦Compose ♦No signup ♦Free ♦
thunderfret.com/tool — D major, coloured by interval
The full guitar fretboard with the D major scale lit up in colour on ThunderFret

Every note, scale and chord — lit up across the whole neck, coloured by interval, mirrored on a piano.

It's possible

Theory and the solo aren't two worlds.

Understand why a chord works, see it light up on the fretboard, drill it, hear it — and the solo stops being magic. It starts being muscle memory you can explain.

// Backstage — 11:42 PM

Study

Quiet room, headphones, the tool open.

  • The Academy course — first chord to modes & odd meters
  • Why the V pulls home, on a fretboard that shows it
  • 17 drills, ear training & a daily streak
// Onstage — Saturday night

Slay

Lights up, crowd loud, and you just know where the notes are.

  • Solo in key without thinking — the Jam band backs you
  • See the next chord coming and land on it
  • Write a riff, then rip a solo over it
Your arsenal

Everything wired to one fretboard.

Learn a concept once and it shows up everywhere else — because it's all the same fretboard underneath.

// Visualise

The full fretboard, live

Any note, scale, chord or interval lights up across the neck — with a keyboard reference to show where octaves land.

// Understand

The why, not the dots

Real explanations of how things are built and why they sound that way — not shapes to mimic and forget.

// Drill

17 adaptive drills

Notes, intervals, sight-reading, chord & scale building, Roman numerals, inversions — Smart practice hunts your weak spots.

// Ear

Train it with an anchor

Intervals, chord quality and degrees by ear, with a reference note you can see and hear. Real ear training.

// Play (Pro)

It hears you play

Play into the mic and your notes light up live as you go, with challenges that check what you actually played — a Pro mode. The mic tuner is free for everyone.

// Compose

Write your own riffs

A free multi-track sketchpad: chords, melodies, editable real tab, a recorded drum kit, even 7/8 bars. Four built-in songs — pop groove to full metal — plus a section mixer and an A–B loop for drilling licks. Then jam over your own track with the Pro band.

// Course

Beginner to advanced, guided

A guided path with milestone badges, practice streaks, a daily theory challenge and a profile that tracks where your time goes. Level 1 of the course is free, and the full course comes with Pro.

// Share

Save, print & share it all

Save any diagram as an image (watermark-free with Pro), print clean charts, and share exact board states or whole riffs as a link.

// Tune

Any tuning, any pitch

Standard, Drop D, DADGAD, opens and full chromatic, with a reference from A 432 to 446.

See inside

It doesn't just tell you — it shows you.

Colour-coded, interactive, and explained in plain English. A few corners of what's waiting inside the tool.

Tapping a note on the fretboard lights up every octave of it on both the guitar and the piano
▸ Tap a note and it lights in every octave — across the whole neck and the piano at once, coloured by octave.
Tapping keys around the circle of fifths as it recolours
▸ The circle of fifths — tap around the wheel and watch every key relate.
The chromatic circle drawing major and minor triads, then all-major-third and all-minor-third patterns
▸ The circle of thirds — stack thirds and watch the shapes draw in: everyday major & minor chords, then the symmetric all-major-third and all-minor-third patterns.
ThunderFret explaining how a C major chord is built from root, third and fifth
▸ Plain-English theory — how each chord is built, and why it sounds the way it does
A piano keyboard with a scale lit up in colour
▸ The same notes mirrored on a piano keyboard, coloured by interval
Step-by-step diatonic chord builder showing why the ii chord is minor
▸ Build any chord in a key step by step — and see why it comes out major or minor
A C major chord voicing lit up on the guitar fretboard with finger numbers
▸ Any chord shown with a real fingering right on the fretboard
Try it yourself →
Plug in

From cold start to charged up in a minute.

01

Enter the tool

Loads instantly in the browser — phone, tablet, laptop. Nothing to install.

02

Explore or follow the course

Attack the fretboard and keys, or take the guided path from your first chord.

03

Drill, tune, rip

Run the workouts, tune up, play into the mic. Smart mode keeps the pressure on your weak spots.

Free theory guides

Learn the why, not just the shapes.

Short, plain-English guides to how music actually works on guitar — chords, scales, the circle of fifths and more. Every one links straight into the interactive tool.

Song breakdowns →Hallelujah chords →Wonderwall chords →First guitar chords →What key is this song? →Why chords sound bad →Memorize the fretboard →Guitar chords →Chord progressions →Scales & modes →Guitar modes →Pentatonic scale →Circle of fifths →Number system →Guitar capo →Intervals →Ear training →
Browse all theory guides →
Pricing

Free to explore. Pro to be taught.

The theory stays free — every chord and tuning, every scale, the full capo, both circles, the Gym, the ear training. Go Pro to create and be taught: the Academy's 56 lessons with your daily assignment and reviews, the multi-track Composer, the Jam band, the mic that hears you play — all of it ad-free. It's also what keeps this indie project alive.

Free

Jump in, no strings

  • Full fretboard & keyboard explorer
  • All 12 keys, every scale & mode
  • Every chord type & tuning, the full capo
  • The full ear-training suite — intervals, chords, rhythm & sing-back
  • Level 1 of the course, streaks, daily challenge & profile
  • Circles of fifths & thirds, songs, gym, mic tuner
Enter the tool
Pro

Unlock everything

  • The Academy — all 56 lessons, a daily assignment & reviews
  • Test-out exams, mastery tracking & spaced repetition
  • Live Play — the mic hears & checks your playing
  • Jam band + solo coach — even over your own riffs
  • The multi-track Composer — riffs, real tab, drums & MIDI
  • MIDI export & watermark-free images
  • The 10 Pro drills, Smart practice, the Harmony guide — and no ads
See Plans

Step on stage.

Open the tool. It's free, it's in your browser, and the only thing between you and the solo is the reps.

Enter the tool