Harmonic Atlas - Scale Chord Explorer

01

Overview

The Harmonic Atlas is a complete music theory reference for any key and scale. It harmonises a chosen scale into full chord stacks - from basic triads through 13th chords - and offers guitar voicings, a circle of fifths, scale relationships, a cadence suggester, and a playable chord progression builder.

The tool covers 35 scales across six families: Major Modes, Harmonic Minor, Melodic Minor, Exotic Scales (inc. Hirajoshi, Whole Tone, Arabian, Phrygian Bebop, Bebop Dominant), Pentatonic (Major, Minor, Blues) and Symmetric diminished (Half-Whole, Whole-Half). Every scale is presented in all 12 keys. Chord tones are always spelled with correct enharmonic names (e.g. B♭ not A♯ in F major). Where a diatonic Maj7 chord has a ♯11 available in the scale, a Δ7♯11 (Lydian chord) is shown as an alternative voicing.

💡 The left column holds reference tools (CoF, scale relationships, cadences, progression builder). The right column always shows the chord view. Both scroll independently.

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Choosing Key & Scale

Use the two dropdowns at the top: Root Key (all 12 chromatic notes) and Scale / Mode. The scale list is grouped by family. Switching either selector instantly updates every panel.

Root Key Sets the tonic of the scale. All note names and chord roots adjust automatically with correct spelling. Scale / Mode Selects from 35 scales across 6 families. Each scale is described in the Scale Hero banner with its characteristic colours and degrees.

🎸 Guitar players: the Scale Hero note pills show the notes in order. Click any pill to jump to that degree's chord cards in the right panel.

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Chord Modes

Two groups of chord mode buttons sit below the selectors. Diatonic modes (gold border) build chords entirely from the scale notes. Chromatic modes (purple border) introduce non-diatonic chords for harmonic colour.

Diatonic modes:

Triads Three-note chords: root, third, fifth. The bedrock of harmony - major, minor, diminished, augmented. 7ths Four-note chords adding the seventh. Adds colour and tension: maj7, m7, dom7, ø7, dim7. 9ths Five-note chords extending to the ninth (compound 2nd). Jazz-standard density - m9, maj9, 9, ø9. 11ths Six-note chords. The eleventh adds suspension-like friction, especially ♯11 in Lydian contexts. 13ths Full seven-note chord stacks. Every scale degree voiced simultaneously - the richest harmonic texture. Others Sus2, Sus4, add9, add11, M6, m6, 6/9, m6/9, augmented, diminished, power chord (5), 7sus4, Maj7sus4, 7sus2 — all built from scale tones where available.

Chromatic modes:

Secondary Dom. V7 chords targeting each diatonic degree (V/ii, V/IV, etc.). Each card shows common alterations — 7♭9, 7♯9, 7♯11, 7♭13, 7♭5, 7♯5 — a ♭II tritone substitution, and a 🎸 voicings button opening guitar chord diagrams for all altered dominant shapes. Secondary Dim. vii° chords a semitone below each diatonic root. Tighter chromatic pull than secondary dominants. Secondary Sub. IV chords a perfect fourth above each degree - the subdominant of each degree, adding modal colour. Chr. Mediants Chords a major or minor third away from the tonic sharing one common tone. Romantic, filmic, surprising.

🎹 Chord symbols follow standard jazz notation. The interval line below each chord name shows exact semitone distances from the root, so you can verify the voicing on any instrument.

04

Scale Hero Banner

The full-width banner directly below the chord mode buttons shows the current scale at a glance: its family, the degree identity line (e.g. 1 2 ♭3 4 5 ♭6 ♭7), and large note pills in scale order. A Steps toggle reveals interval arcs between each note pill showing the semitone distance (½ = half step, 1 = whole step, 1½ = minor 3rd, 2 = major 3rd).

Below the note pills, a live treble-clef staff shows the ascending scale in standard notation — noteheads, stems, accidentals, and ledger lines rendered in real time. A small ▶ play button sits to the left of the staff; clicking it plays the scale up one octave, clicking again stops it.

The right panel shows a concise description of the scale's characteristic colour and harmonic applications.

👆 Clicking any note pill scrolls the chord panel to that scale degree's chord cards. The ♩ icon on each chord card opens an inline stacked-chord staff notation for that chord. The search history strip above the banner shows your recent key+scale navigations.

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Circle of Fifths

The Circle of Fifths arranges all 12 keys clockwise by ascending perfect fifths. The outer ring shows major keys, the middle ring their relative minors, the inner ring diminished chords.

Segments highlighted in gold are major chords of your scale; purple are minor chords; orange are diminished chords. Keys adjacent on the circle share the most common notes — useful for modulation planning.

🖱️ Hover works in both directions: hover any CoF segment to highlight the matching chord card (and see a tooltip with name + quality) — including non-diatonic positions. Conversely, hover any chord card to highlight its slice on the circle.

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Chord Views

Three tabs above the right panel switch the display mode for all chords:

Chord List Default view. Each degree shows one card with the chord symbol, quality, note names, and interval stack (e.g. 1 · ♭3 · 5 · ♭7). Guitar Four sub-tabs for guitar-specific views:

Basic SVG fretboard diagrams for each chord. The algorithm prioritises the root as bass note (lowest sounding pitch). Shapes requiring a barre are shown with a purple bar across the relevant strings and a small B marker. Gold dot = root, purple = other chord tones. Arpeggios Horizontal fretboard diagrams showing ascending arpeggio shapes for 7th chords across the CAGED system (E, A, D, G, C forms). Each shape covers a compact 5-fret window with the root on a specific string. Notes ascend in R–3–5–7 order. Only available in 7th chord modes. Drop 2 Jazz voicing: the 2nd-highest note of a close-position chord dropped one octave. Shows all 4 inversions × 3 string sets (E-A-D-G, A-D-G-B, D-G-B-e). No open strings. Inversion label shown as slash notation, e.g. Gmaj7/B for 1st inversion. Drop 3 Jazz voicing: the 3rd-highest note dropped one octave. Wider, more open voicings on non-adjacent string sets. Same 4 inversions × 3 sets. Used in big-band arranging. Click any diagram to zoom. Alt. Dom Altered dominant voicings for all dominant chords in the current key (V7, secondary dominants). Covers 9 chord types: 7♭9, 7♯9, 7♯11, 7♭13, 7♭9♭13, 7♭5♭9, 7♭5♯9, 7♯5♭9, 7♯5♯9. Each shows up to 3 moveable shapes (E-str., A-str., D-str.) with the root on a different string. Shapes are compact (span ≤ 4 frets). A tritone-substitution note is shown for each root. Only appears when the scale contains dominant chords.

Mandolin Three sub-tabs for mandolin (G-D-A-E tuning):

Chords Standard mandolin chord diagrams, may include open strings. Click to zoom. Scale Full fretboard scale map for mandolin. Swipe horizontally on mobile. Chop Chop chords — closed (moveable) shapes with no open strings, shown for both triads and 7th chords. Strike and immediately mute by releasing finger pressure for the classic backbeat chop on beats 2 & 4. These shapes can be moved anywhere on the neck.

🎸 Drop 2 and Drop 3 voicings follow the jazzguitar.be standard. Arpeggio shapes use the CAGED system to map 5 positions across the fretboard for each 7th chord.

👆 Diagram zoom & navigation: click any chord diagram to open it enlarged. Use the ◀ ▶ buttons, swipe left/right, or arrow keys to navigate between all diagrams in the current view. The previous and next chord names are shown as context labels so you know what's coming before you swipe.

🖥️ Two-column chord list: on screens ≥ 900 px wide, the Chord List view arranges degree sections in two columns for a more compact overview.

07

Scale Relationships

This collapsible panel (left column) shows three groups of related scales. Each chip now shows a brief explanation of why the two scales are related. Click any chip to instantly navigate to that scale — handy for modal interchange and modulation planning.

Relative Scales that share every note but start on a different root. The chip shows which mode of the current scale it corresponds to — e.g. "3rd mode of Major (Ionian) — same 7 notes." Parallel Scales with the same root but different note sets. The chip shows how many notes differ and which ones — e.g. "Same root, 1 note different (Bb altered)". Closely Related Scales differing by only one note with a root a semitone or two away — the subtlest modulation targets. Shows shared note count and root distance.

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Cadence Suggester

Seven common cadences pre-built from your scale's actual chords. The final (resolving) chord of each cadence is highlighted in gold. Click any chord chip to add it to the Progression Builder.

Perfect V–IStrongest closure in tonal music. Dominant to tonic. Plagal IV–IThe "Amen" cadence. Soft, hymnal, conclusive. Deceptive V–viSurprise resolution to the submediant instead of tonic. Half I–VEnds on the dominant - unresolved, expectant. ii–V–IThe backbone of jazz harmony. IV–V–IClassic pop/rock full cadence. vi–IV–I–VThe "axis" progression - I–V–vi–IV permutation widely used in pop.

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Progression Builder

Build and play chord progressions with the Salamander Grand Piano sampler. The builder is collapsed by default and opens automatically the first time you add a chord.

Adding chords Hover any chord card and click the + button, or click any chord chip in the Cadence Suggester. Chords are added as slots to the strip. Reordering Drag slots left or right to reorder, or use the ◀ ▶ arrow buttons on each slot for one-step moves — useful on mobile where drag-and-drop is tricky. Per-chord duration Each slot has independent − / + controls to set how many beats that chord lasts (1–16). The global Beats/chord sets the default for new additions but you can override any slot independently. BPM Tempo from 40 to 240 BPM. Changes take effect at the next playback. Rhythm Six strum patterns (Straight, Folk, Rock, Ballad, Bossa, Waltz) shape the rhythmic feel within each chord — from simple block chords to syncopated arpeggiation. The pattern applies to all chords in the progression. Substitutions Each chord slot shows a ≈ button on hover. Clicking it opens a context-aware menu — sus chords, relative major/minor, tritone sub (for dom7), augmented and diminished alternatives, and half-step approach chords. Metronome Toggle a click track or kick+snare drum pattern alongside playback. Loop Cycle the progression indefinitely until you press Stop. The Loop button lights up gold when active. Presets Load classic progressions (I–IV–V–I, ii–V–I, etc.) instantly transposed to your current key. Expand The expand button opens a fullscreen overlay with larger chord slots, a progress bar, and all transport controls mirrored.

09b

Composition & Improvisation

The purple ♩ button (top-right) opens the Composition tool — a full-featured sequencer for building, saving, and practising over chord progressions. Multiple compositions are saved in the browser (localStorage) and persist across reloads.

Building a progression

+ New Creates a blank composition. Give it a title by clicking the name field. Search bar Type any chord name (e.g. "Cm7", "Fmaj7", "G7") to find and add chords. Results are filtered live. ↙ Import Copies the current progression builder into the composition instantly. ◀ ▶ Reorder chords within the composition without stopping playback. ≈ Substitutions Chord substitution popover — sus chords, relative major/minor, tritone sub, approach chords.

Per-chord controls

F / A Full — strum the whole chord. Arp — play notes one at a time in sequence. Note value Whole / Half / Quarter / 8th / 16th — sets how fast notes repeat (strum rate for Full, step speed for Arp). This actually affects the sound — 16th is four notes per beat. Arp pattern ↑ Up · ↓ Down · ↑↓ Up-Down · ↓↑ Down-Up. Visible only in Arp mode. − / + Beat count for this chord (1–16 beats).

Global controls (All row)

Full / Arp ↑↓↕ Set every chord to the same mode at once. Note value dropdown Apply the same speed to all chords in one click.

Playback

BPM40–240. Changes take effect at the next loop cycle. LoopCycles indefinitely. Adding, removing, or reordering chords during playback takes effect at the next cycle — no need to stop. StrumRhythmic feel for the whole composition — Straight, Folk, Ballad, Pop, Jazz, Funk, Reggae, Bossa, Waltz… SwingStraight / Light / Medium / Hard — delays off-beat notes to create swing or shuffle feel. DrumsSynthesized drum pattern (Web Audio API). Style selector: Auto (matches strum pattern), Rock, Funk, Jazz, Bossa, Waltz, Ballad, Reggae, HiHat, Click. SoundPiano — Salamander Grand Piano samples. Guitar — real acoustic guitar samples (loads on first use).

♪ Improvise — the overlay

Open the Improvise view during playback to see the current chord in full-screen focus. This is designed for playing along in real time.

Chord nameLarge chord symbol and Roman numeral highlight what's playing right now. Note bubblesAll notes of the chord displayed as pills — use them as anchor tones when improvising. What to playQuality-based scale suggestions — determined by the chord type, not the key degree:
Δ7 → Ionian, Lydian, Major Pentatonic
dom7 → Mixolydian, Lydian Dominant (#11)
dom7b9 / altered → Altered scale (b9 #9 #11 b13)
m7 → Dorian, Aeolian, Minor Pentatonic
ø7 → Locrian, Locrian ♯2
dim7 → Diminished (H-W) or (W-H)
aug → Whole Tone, Lydian Augmented Next chordPreview of the upcoming chord so you can prepare your line. TimelineAnimated playhead showing your position within the loop. Segments proportional to chord beat counts. ⏸ PauseLarge circular button (top-right of overlay) — pause and resume without leaving the improv view. Touch-friendly on mobile.

🎸 Workflow: set up a ii–V–I loop, switch to Guitar sound, open Improvise, and use the scale suggestions to practise over each chord change in real time. The next-chord preview gives you one bar to prepare your phrase.

10

Negative Harmony

Popularised by Jacob Collier (from Ernst Levy's theory). Every note of a chord is mirrored around an axis between the tonic and its perfect fifth. The result inverts the harmonic polarity: major chords become minor, dominant 7ths become half-diminished.

C maj → C min (neg) G7 → Cø7 (neg) Am → F (neg)

The axis is shown as a red dashed line on the Circle of Fifths, with arcs connecting mirrored pitch pairs. Only available in Ionian (Major) mode. When active, the Circle of Fifths shows only the mirror arcs (diatonic highlights are suppressed).

Original card Left card — the diatonic chord as usual. Negative card Right card — the mirrored chord with its own guitar voicing diagram. Hover the pair to see a tooltip showing how each note transforms (e.g. C → G, E → E♭, G → C, B → A♭ for Cmaj7). Persistence The toggle state is saved. If you switch to another scale and return to Ionian, Negative Harmony re-activates automatically.

🪞 Use negative harmony to find unexpected chord substitutions — the negative of a ii–V–I in C major is a iii–II–I progression, giving a completely different colour with the same functional logic.

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Scale Comparison

The Compare Scales → Side by Side button (above the Scale Hero) opens two selector pairs and displays two scales' chord lists side by side. Chords shared between both scales are marked with a ◆ SHARED badge - useful for finding pivot chords when modulating between keys.

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Pro Tips

🔁Modal interchange: stay in C Major but click a Dorian or Mixolydian scale chip from Scale Relationships - you can drag their chords into the Progression Builder to borrow modal colour.

🎯Finding pivot chords: use Compare mode to put your current key and target key side by side - the SHARED chords are your pivot candidates for a smooth modulation.

🎷Jazz voicing workflow: switch to 7ths mode → use Drop 2 view to find voicings → add the chords to the builder → switch to Guitar Diagrams to check fingering.

🌐Circle of Fifths navigation: hover adjacent segments to hear (visually) how close two chords are - gold + purple neighbours make the smoothest voice-leading moves.

⚡Quick progressions: click a Cadence Suggester row chord-by-chord to assemble a full cadence in the builder, then hit Play to audition it instantly.

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Sources & Further Reading

Useful references for going deeper on the music theory covered in this tool.

🎸 Jazz Guitar - Chords & Voicings: jazzguitar.be - comprehensive chord theory, shell voicings, Drop 2 & Drop 3 guides. The most useful single guitar theory resource online.

🎹 Jazz Piano & Extensions: thejazzpianosite.com - clear explanations of 9ths, 11ths, 13ths and altered tensions with practical voicing examples.

📖 Music Theory Fundamentals: musictheory.net - free interactive lessons covering intervals, chords, modes, and more. Great for beginners.

🪗 Mandolin Chords: mandolincafe.com/chords - chord charts and community discussion. The chop chord technique is a staple of bluegrass and Western swing rhythm playing.

🎵 Scale & Mode Reference: ianring.com - exhaustive catalogue of scales with interval structures, names, and relationships.

📚 Recommended Books: Mark Levine - The Jazz Theory Book (Sher Music); Jerry Bergonzi - Inside Improvisation Vol.1: Melodic Structures; Ernest Levy - A Theory of Harmony (negative harmony source).

📺 Negative Harmony: Jacob Collier's interviews (Nonesuch Records) explain the practical application; Adam Neely's YouTube explanation is the clearest visual introduction available.