Import — paste chord names (e.g. "C G Am F") or a Harmonixly share link
𝅲 Your Progression
♩ Piano
♿ Chord Picker
🎵 Famous Progressions
♫ About Harmonixly
Why this project?
Chord progressions are the harmonic backbone of virtually every song ever written. While plenty of tools exist for looking up individual chords or generating random progressions, there is a gap: no free, focused tool lets you build and hear chord progressions with real-time degree analysis and mood identification — all in one place, with no signup required.
What is it?
Harmonixly is an interactive chord progression builder and chord theory explorer. Select a key and scale, then click chords from the picker or use the piano keyboard to construct progressions. Each chord shows its degree analysis, and the entire progression plays back through a synthesized piano sound. Famous song progressions are included as presets you can load and modify. You can also upload an audio file and Harmonixly will automatically detect the chord progression, making it easy to reverse-engineer songs you love.
With the Explore tab you can study 26 chord qualities — from basic triads to extended, altered, and suspended chords — hear each interval played individually, compare chords across all 12 keys, and learn the theory behind every chord type. Extended chords are fully integrated into the progression builder, so you can go beyond diatonic triads and sevenths when building your progressions.
How does it work?
Chord data: All 12 major and minor keys with their diatonic triads, seventh chords, and common borrowed chords are precomputed from music theory rules. A reference database of 26 chord types (triads, sevenths, extended, altered, suspended, and special) powers the Explore tab.
Explore tab: Gives you a searchable, filterable grid of all 26 chord types. Click any card to open a detailed modal with three views: Interval Stack (visual breakdown of each note and its interval with per-interval playback), All Keys (comparison table showing the chord in all 12 keys with play buttons), and Play (full chord playback). Each chord type includes a plain-English description and real-world usage examples.
Extended chords: Non-diatonic chord types (9ths, 11ths, 13ths, altered sevenths, power chords, clusters, tritones, etc.) are generated per key and available alongside diatonic and borrowed chords for building richer progressions.
Degree analysis: Each chord is mapped to its scale degree (I, ii, iii, IV, V, vi, vii°) using the key signature. Borrowed chords use flat/sharp accidentals in the degree.
Audio playback: Uses the Web Audio API with multiple oscillator nodes per chord (one per note), shaped by ADSR envelope gain nodes and a lowpass filter for a warm piano-like tone.
Mood detection: Pattern matching against known progression templates (e.g., I-V-vi-IV = "Pop Anthem", i-bVII-bVI = "Andalusian") identifies the emotional character of your progression.
Inversions: Click the "inv" button on any chord slot to cycle through root position, 1st inversion, and 2nd inversion (triads) or 1st/2nd/3rd (sevenths).
Save & Share: Progressions are saved to localStorage and can be shared via URL-encoded links.
Audio Analysis: Upload an MP3 or WAV file and Harmonixly uses chroma feature extraction and template matching to automatically detect the chord progression, key, and tempo.
How to use it
Select a key from the dropdown (C, C♯, D, etc.) and choose Major or Minor scale.
Add chords by clicking chord cards in the Chord Picker below.
Reorder chords by dragging and dropping slots left or right.
Change inversions by clicking the "inv" button on any chord slot to cycle through positions.
Switch tabs between Diatonic, Borrowed, and 7ths for different chord types.
Use the Explore tab to study 26 chord qualities. Browse all types or filter by category (Triads, Sevenths, Extended, Altered, Suspended, Special) and search by name or symbol.
Open a chord's detail modal by clicking any Explore card. View the Interval Stack to see how each note is built, all-keys comparison to hear the same chord in every key, or play individual intervals to train your ear.
Add extended/altered chords to your progression — any chord type from the Explore grid can be added to your working progression and played with the rest.
Play / Loop your progression. Toggle Loop to repeat indefinitely.
Get inspired with the 🌟 Inspire button for random progressions.
Save your work locally, Share via copyable link, or Import from text.
Remove chords by hovering and clicking the × button, or Clear to reset.
Load presets from the Famous Progressions section.
Analyze audio by dragging or browsing to upload an MP3 or WAV file — Harmonixly will detect the chord progression, key, and BPM automatically. Click "Load as Progression" to use the results in your working progression.
Found a bug, have a feature request, or just want to say hi? Fill out the form below or email us directly at info@harmonixly.com.
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🎧 How Audio Analysis Works
When you upload an audio file, Harmonixly runs it through a multi-stage analysis pipeline on the server. Here is exactly what happens:
Step 1: Decode & Clean
Your audio file is loaded and resampled to a standard rate. Leading and trailing silence is trimmed automatically. The audio is normalized to a consistent volume level so the analyzer doesn't miss quiet passages.
Step 2: Fused Chroma Extraction
Two different spectral representations are computed for every frame of audio:
STFT Chroma — a short-time Fourier transform captures the frequency energy of each pitch class.
CQT Chroma — a Constant-Q Transform provides better resolution at lower frequencies where chords have their fundamental tones.
Both are averaged into a fused chroma vector (12 pitch classes × time). This gives the analyzer a highly detailed harmonic fingerprint of every moment in the song.
Step 3: Key Detection
Two independent methods determine the key:
Krumhansl-Schmuckler — compares the average chroma profile against major and minor key profiles derived from centuries of Western music.
Tonal Centroid — uses a machine learning classifier for additional confidence.
For songs with key changes, the dominant key (the one present across the most frames) is reported.
Step 4: Chord Template Matching
Every frame is compared against 84 chord templates (12 roots × 7 qualities: major, minor, dominant 7th, major 7th, diminished, sus2, sus4) using cosine similarity. The best-matching chord and its confidence score are recorded for each frame.
Step 5: Smoothing
Raw frame-by-frame results are noisy. A sliding window majority vote (2-second window, weighted by confidence) stabilizes the results while preserving real chord changes. Brief glitches are removed.
Step 6: Timeline Consolidation
The smoothed results are grouped into 4-second windows. For each window, the chord that occupies the most time is selected. This collapses brief transitional chords and surfaces the dominant harmony in each section.
Step 7: Display Simplification
Complex chord qualities are mapped to simple names for readability:
A:maj7, A:7, A:maj → "A"
F#:min → "F#m"
D:sus2, D:sus4 → "D"
Step 8: BPM Estimation
Onset detection finds where loud transients (drum hits, strums) occur. Multiple passes (median + mean) estimate tempo, with automatic correction for double-time and half-time ambiguity.
Accuracy
~85% — clean pop/rock recordings with clear chord changes
~70% — heavily produced tracks with dense instrumentation
~50% — electronic, jazz, or songs with extended chords / rapid changes
The "Load as Progression" button maps detected chords to Roman numeral degrees in the context of the detected key, so you can hear and modify the result immediately.
🔒 Sign In
Sign in to save your progressions to the cloud and access them from any device.
Your progressions are stored securely. We only need basic profile info.
Interval Stack
Notes in Every Key
Key
Chord
Notes
Switch to the Intervals tab to hear individual intervals.
