Guitar · Ukulele · Banjo · Bass
Music theory, mapped to your fretboard.
GTK is a family of player's toolkits for iPhone, iPad and Mac (for iOS). Chords, scales, triads, tuner and metronome – built by a player to show where the theory lives under your fingers.
$9.99 one-time · no ads · no subscriptions · works offline
The family
Pick your instrument
Each app is built around its own instrument – its tunings, its fret count, its chord shapes – while sharing the same tools and design.
Guitar
Tools for your guitar journey
- Chords
- ~3,600 chords
- Tunings
- 8
Ukulele
Tools for your ukulele journey
- Chords
- 4,200+ voicings
- Tunings
- 4
Banjo
Tools for your banjo journey
- Chords
- 10,000+ chord entries
- Tunings
- 8
Bass
Tools for your bass journey
- Chords
- 582 chords
- Tunings
- 9
The idea
Not a theory course. A map.
You don't need another lecture on the circle of fifths. You need to see which notes are under your hand right now, hear how they sound, and practise until it sticks.
See it
Every scale, chord, triad and position drawn on a fretboard that matches your instrument and tuning.
Hear it
Play chords strummed or arpeggiated, and hear the notes you're learning as you drill them.
Drill it
Tempo-driven note and triad practice that turns knowing into finding – without thinking.
- One-time purchaseNo subscriptions, no in-app purchases, no ads.
- Works offlineEverything runs on your device. No account, no internet needed.
- No data collectedAudio for the tuner is processed on-device and never recorded or sent.
- Family SharingBuy once and share with up to six family members.
What's inside
17 tools in every pocket
Chords
- Chord MasterBrowse by key, build chords note by note, or place your fingers on the fretboard to name a chord – then hear it whole or arpeggiated.
- Chord LibrarySearchable chord diagrams with strict or fuzzy matching, key filters, diatonic and borrowed chords, and favourites.
- Custom ChordsCreate your own voicings, name them yourself or let GTK detect the name, play them whole or arpeggiated, and export them to share.
- Chord BuildCreate your own chord: place fingers, mark strings open or muted, and let GTK detect the name.
- Chord ExploreSelect notes, or tap string and fret positions, and GTK names the chord.
- Chord TransposerMove a song’s chords to any key, with capo positions taken into account.
Theory
- ScalesScales, modes, pentatonics and world scales on a colour-coded fretboard, with a Positions view that shows shapes rather than note names, plus diatonic chords and Triads and Chords tabs.
- Scale SharingLayer up to four scales on one fretboard, with shared notes as pie-slice dots and roots, 3rds and 5ths ringed.
- Triad SharingBuild a progression and see each chord’s triad tones on one fretboard, colour-coded per chord, with shared frets as pie-slice dots.
- Chord SharingType any chord name to map its notes across the fretboard with the root ringed, and compare it with up to three other chords.
- Position FinderChoose where on the neck you want to play and see a key’s notes right there – so you can stop sliding up and down the fretboard.
- Circle of FifthsTap any key to see its modes, diatonic chords, Roman numerals and key signature.
- Mode ConverterSee how one mode becomes another, note by note and semitone by semitone.
Practice
Side by side
Which tools are in which app?
| Feature | Guitar | Ukulele | Banjo | Bass |
|---|---|---|---|---|
| Chords | ||||
| Chord Master | Included | Included | Included | Included |
| Chord Library | Included | Included | Included | Included |
| Custom Chords | Included | Included | Included | Included |
| Chord Build | Included | Included | Included | Included |
| Chord Explore | Included | Included | Included | Included |
| Chord Transposer | Included | Included | Included | Included |
| Theory | ||||
| Scales | Included | Included | Included | Included |
| Scale Sharing | Included | Included | Included | Included |
| Triad Sharing | Included | Included | Included | Included |
| Chord Sharing | Included | Included | Included | Included |
| Position Finder | Included | Included | Included | Included |
| Circle of Fifths | Included | Included | Included | Included |
| Mode Converter | Included | Included | Included | Included |
| Practice | ||||
| Note Practice | Included | Included | Included | Included |
| Triad Practice | Included | Not included | Not included | Included |
| Utilities | ||||
| Tuner | Included | Included | Included | Included |
| Metronome | Included | Included | Included | Included |
Full comparison with tunings, fret ranges and chord counts →
Built with players
Every update starts with feedback
GTK is under constant development, and many new features began as a message from a player. Found a bug or want a tool? Tell us.