Every Music Theory Tool
You Actually Need — Free
Six interactive tools covering chords, scales, modes, the circle of fifths, chord progressions, and chord substitutions. No signup required. Works on any device. Built for pianists, songwriters, and anyone who wants to understand music better.
Six Tools. Everything Covered.
Each tool is built to do one thing exceptionally well — and together they cover every fundamental area of music theory a working musician needs.
Select any root key and scale type — instantly see all the notes and the complete set of diatonic chords that belong to it. Covers all 7 modes, natural and harmonic minor, pentatonic scales, and the blues scale.
See exactly which piano keys to press for any chord in any key. The most comprehensive visual chord reference online — from basic triads to extended 9th chords, with inversions shown on a real piano keyboard.
Click any key on the interactive circle of fifths and instantly see its diatonic chords, relative minor, and neighboring keys. The essential tool for understanding key relationships, modulation, and transposition.
Pick a key and a vibe — get four ready-to-use chord progressions with the actual chord names filled in, Roman numeral analysis, and a plain-English description of why each one sounds the way it does.
Playing notes you don’t know the name of? Click them on the keyboard and find out instantly. The tool identifies the chord, its type, inversion, and any missing notes — and shows you the complete chord for reference.
Build a chord progression, click any chord, and get intelligent substitution suggestions grouped by emotional effect — with an explanation of why each one works and how it interacts with the surrounding chords.
Built for Real Musicians
Whether you’re just starting out or filling in gaps in your theory knowledge, these tools meet you where you are.
Ready to Put It All Together?
The tools are free forever. But if you want a guided path through everything — from what a scale degree is to writing your own chord progressions with intentional substitutions — the Chordopedia Crash Course was built for exactly that.
Free Online Music Theory Tools — What Each One Does
Chordopedia’s suite of free interactive music theory tools is built for one purpose: to make music theory genuinely useful in real creative situations. Not just something you memorize for an exam, but something you reach for while you’re writing, practicing, or trying to figure out what you just played.
Every tool works in all 12 keys, handles both sharp and flat enharmonic spellings, and is designed to be used without any prior music theory knowledge. You can start anywhere.
The Scale & Chord Finder — Find Any Scale in Any Key
The Scale & Chord Finder shows you the notes of any scale in any key — and automatically generates the complete set of diatonic chords that belong to it. Select G major and you instantly see G, A, B, C, D, E, F# along with the seven diatonic chords (G, Am, Bm, C, D, Em, F#dim) labeled with their Roman numerals. Switch to G Dorian and the notes and chords update instantly to reflect the mode change.
The tool covers all seven modes (Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, Locrian), natural and harmonic minor, pentatonic major, pentatonic minor, and the blues scale. Every note is spelled correctly using the diatonic spelling engine — so you’ll never see two of the same letter name in one scale.
The Piano Chord Library — See Every Chord on a Keyboard
The Piano Chord Library is the most visual chord reference tool online. Select any root key and chord type and the tool highlights exactly which piano keys to press — with the root note marked separately from the other chord tones. It covers 17 chord types including major, minor, dominant 7th, major 7th, minor 7th, sus2, sus4, diminished, diminished 7th, augmented, minor major 7th, add9, 6th, minor 6th, dominant 9th, major 9th, and minor 9th — all in all 12 keys, in root position and all inversions.
The Circle of Fifths Tool — Understand Key Relationships
The Circle of Fifths Chord Wheel is an interactive version of the most famous diagram in music theory. Click any key segment to see its complete diatonic chord set, its relative minor, and its position relative to neighboring keys. This tool is essential for understanding modulation (changing keys), finding pivot chords for smooth key changes, and transposing progressions from one key to another.
The Chord Progression Generator — Ready-to-Use Progressions by Mood
The Chord Progression Generator takes the guesswork out of starting a new song. Select a key and an emotional vibe — Happy, Sad, Tense, Epic, Romantic, Bluesy, or Jazz — and get four ready-to-use chord progressions with the actual chord names filled in for that key. Each progression includes Roman numeral analysis and a plain-English explanation of why it sounds the way it does. Major-key vibes use the major scale. Minor-key vibes use the natural minor scale with correct diatonic spelling.
The Chord Identifier — Find the Name of Any Chord
The Chord Identifier answers the question every musician faces: “What chord am I playing?” Click the notes on the interactive keyboard and the tool identifies the chord name, type, and inversion — including whether any notes are missing. It handles triads, seventh chords, extended chords, inversions, and partial voicings. Set the key context to get correct enharmonic spelling for flat keys.
The Chord Substitution Tool — Make Your Progressions More Interesting
The Chord Substitution Tool is Chordopedia’s flagship tool. Build a chord progression using the diatonic chord row, click any chord in your progression, and get intelligent substitution suggestions grouped by emotional effect — Smoother, Darker, Brighter, Jazzier, More tension, More epic, and Surprising. Every suggestion includes an explanation of why it works harmonically and how it interacts with the next chord in your progression. The tool also analyzes your progression’s harmonic function, flags missing functions, and offers a smart context-aware suggestion for every chord position.
Why Free Music Theory Tools Matter
Music theory has historically been gatekept behind expensive lessons, dense textbooks, and academic environments that treat it as an end in itself rather than a creative tool. The result is that most working musicians — even very good ones — have significant gaps in their theory knowledge that they work around rather than through.
Chordopedia exists to change that. Every tool on this page is free because the knowledge behind it should be accessible to anyone who makes music, regardless of their background or budget. Understanding why a chord works, what function it serves, and how to substitute it for something more interesting shouldn’t require a music degree.
If you want to go deeper — to understand the theory behind the tools rather than just using them — the Chordopedia Crash Course is a structured 45-minute journey through everything from scale degrees to chord substitutions, with these tools embedded at every step.