Guitar Codex

Guitar Codex is the app you reach for every time you pick up a guitar. Tune up, check a chord, run a scale, or sit down for a proper lesson. It works for total beginners and for players twenty years in.

THE TOOLS

• Chromatic tuner with a smooth needle and presets for Standard, Drop D, Open G, DADGAD, and more. Reference pitch is adjustable from 432 to 445 Hz.
• Metronome with tap tempo, time signatures, and a visual beat indicator.
• An interactive circle of fifths: tap any key and see its seven chords, its key signature, and its relative key.

THE LIBRARIES

Every chord, scale, arpeggio, and triad renders on the same big, high-contrast fretboard diagram, with each note color-coded by its job in the shape: root, 3rd, 5th, and so on. You learn why a shape works, not just where your fingers go.

• Chords: every common type and voicing, with CAGED positions up the whole neck
• Scales: five boxes per scale, a full-neck view, and advice on when to use each one
• Triads: three string sets, three inversions each, all on one page
• Arpeggios: chord tones mapped across the neck for every quality

THE COURSE

140 lessons in 12 modules take you from holding the guitar for the first time through chords, scales, theory, the CAGED system, progressions, modes, songwriting, technique, genre studies, and fretboard and ear mastery. Lessons teach with diagrams and real songs, and every one ends with a short Try It exercise you can do with the guitar in your hands. All of Module 1 is free.

PAY ONCE, OWN IT FOREVER

Guitar Codex has no subscription and never will. The free version includes the full tuner, the metronome, and a real taste of everything else. Two optional one-time purchases unlock the rest: Pro, the complete reference toolkit, and Complete, which adds all 140 lessons plus every lesson added in the future. Buy it once and it is yours for good.