Chord Analyzer

Chord Analyzer is a real-time MIDI chord detection and music theory analysis plugin — completely free.

Overview

Route MIDI to Chord Analyzer and instantly see what chord you’re playing, its Roman numeral in your chosen key, and its harmonic function. Get intelligent suggestions for what chord to play next, from basic I-IV-V progressions to advanced chromatic mediants and Coltrane changes.

Features

Chord Detection

Recognizes 45 chord types including triads, seventh chords, extended chords (9th, 11th, 13th), altered dominants, sus chords, and power chords. Detects inversions and displays slash notation.

Music Theory Analysis

Set your key (any root, major or minor) and see Roman numeral analysis for every chord. Harmonic function labels (Tonic, Subdominant, Dominant, Borrowed, Chromatic) help you understand the role each chord plays.

Chord Suggestions

Three tiers of suggestions based on your current chord:

• Basic — Common progressions (I-IV-V, ii-V-I, vi-IV)
• Intermediate — Secondary dominants, borrowed chords, tritone substitutions
• Advanced — Chromatic mediants, Neapolitan chords, augmented 6th approaches

Session Recording

Record your chord progressions with timing data and export as JSON for analysis, notation software, or further processing.

Educational Tooltips

Hover over any element to learn about chord qualities, harmonic functions, and why certain progressions work.

Three Versions

Chord Analyzer ships in three versions to cover every plugin host:

All three share the same chord-detection engine. The difference is how your host classifies and renders the plugin:

• MIDI variant sits in the dedicated MIDI / Note FX slot of modern DAWs and brings the full visualizer with it.
• Headless variant declares native LV2 output control ports so headless LV2 hosts (Zynthian, etc.) can display the detected chord in their own UI without ever loading our visualizer.

If you’re on a desktop DAW, use the MIDI variant. If you’re on Zynthian or any LV2 host that doesn’t run a plugin GUI, use the Headless variant.

DAW Setup Guide

Bitwig Studio

1. Add your synth to a MIDI track as normal
2. In the device chain, click + before your synth
3. Search for “Chord Analyzer MIDI” in the Note FX category and add it
4. MIDI passes through automatically — your synth still receives all notes

Reaper

1. Open the FX chain on your MIDI/instrument track
2. Click Add and search for “Chord Analyzer MIDI” (VST3)
3. Drag it above your synth in the chain
4. MIDI passes through to your synth automatically

Logic Pro

1. On your instrument track, click the MIDI FX slot (above the Instrument slot)
2. Choose Chord Analyzer MIDI under Dusk Audio
3. The plugin receives MIDI from the track and passes it through to your instrument

Cubase / Nuendo

1. On your instrument track, add “Chord Analyzer MIDI” as a MIDI insert
2. The plugin receives MIDI from the track automatically
3. Your instrument remains unchanged

Ableton Live

Ableton doesn’t list MIDI-only plugins in MIDI tracks the same way other DAWs do, so use the instrument version with an Instrument Rack:

1. Load your synth on a MIDI track as normal
2. Select your synth and press Cmd+G (Mac) or Ctrl+G (Windows) to group it into an Instrument Rack
3. Click the Show Chain List button (three horizontal lines on the left side of the rack)
4. Right-click in the empty space below your synth’s chain and choose Create Chain
5. Drag “Chord Analyzer” (the instrument version, not MIDI) from the browser into the new empty chain
6. Both chains receive the same MIDI — your synth produces sound, the Chord Analyzer shows chords

FL Studio

Use the instrument version with Patcher:

1. Add a Patcher instance to your channel rack
2. Inside Patcher, add both “Chord Analyzer” and your synth as nodes
3. Route the MIDI input to both plugins in parallel
4. Route only your synth’s audio output to the Patcher output
5. Both plugins receive MIDI — your synth produces sound, the Chord Analyzer shows chords

Desktop LV2 Hosts (Ardour, Carla)

Use Chord Analyzer MIDI — declares no audio ports, full custom visualizer in the host plugin window.

1. Add “Chord Analyzer MIDI” to the MIDI chain before your synth
2. MIDI passes through to the next plugin in the chain
3. Open the plugin to see the full chord display

Headless LV2 Hosts (Zynthian)

Use Chord Analyzer Headless — it exposes the detected chord through native LV2 output control ports so the host can render it in its own UI.

1. Install the bundle from the chord-analyzer-headless-*.zip (separate download)
2. Add “Chord Analyzer Headless” to your MIDI chain before your synth
3. The detected root, quality, bass and inversion appear as live values in your host’s plugin parameter view

Installation

The main download includes “Chord Analyzer” and “Chord Analyzer MIDI” — install whichever your DAW uses. The “Chord Analyzer Headless” variant ships in a separate -headless- zip aimed at Zynthian and other headless LV2 hosts; download it only if you need it.

Open Source

Chord Analyzer is free and open source. Source code is available on GitHub.