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EarthmanMuons/whatchord · source
Snapshot 0 · 2026-11-04T12:47:28Z · Dart · 0BSD
Content fingerprint
011b5efd292c31107ae01e254acacfc7a01f311bc04a641d391a8932c4426b45GitHub description at capture
Interactive chord identification and harmony exploration, with live MIDI and manual input
README at capture
<p align="center">
<img width="200" src="docs/site/public/images/whatchord_logo.webp" alt="WhatChord logo">
</p>
<h1 align="center">WhatChord</h1>
<p align="center">
<a href="https://apps.apple.com/us/app/whatchord-midi/id6758409779">
<img
src="docs/site/public/images/Download_on_the_App_Store_Badge_US-UK_RGB_blk_092917.svg"
alt="Download on the App Store"
style="height: 60px"
hspace="15"
/></a>
<a href="https://play.google.com/store/apps/details?id=com.earthmanmuons.whatchord">
<img
src="docs/site/public/images/GetItOnGooglePlay_Badge_Web_color_English.svg"
alt="Get it on Google Play"
style="height: 60px"
hspace="15"
/></a>
</p>
WhatChord is an interactive chord identification, key detection, and harmony
exploration app. Identify voicings from live Bluetooth or USB MIDI input or
manual note entry, follow the key as you play, then explore chords, scales,
keyboard patterns, and harmonic context. It is optimized for speed, accuracy,
and musician-expected naming, favoring stable, conventional interpretations over
simple note-matching.
**Website:** <https://whatchord.earthmanmuons.com>
**Try chord identification online:** <https://whatchord.earthmanmuons.com/try>
---
## Features
- **Live chord identification**\
Connect a Bluetooth or USB MIDI keyboard and see chords update instantly as
you play. Clear polychords played as distinct chordal layers are shown in
familiar stacked notation.
- **Automatic key detection**\
Auto mode listens to your recent live chords, estimates the current key, shows
confidence across all 24 major and minor keys, and can keep the app's key
context following your playing. When the evidence is ambiguous, it waits
instead of guessing.
- **Manual chord lookup**\
Enter notes directly to identify a chord from any instrument, sheet music, or
recording. The first note entered sets the bass.
- **Explore chords**\
Tap the chord card to open explore mode and try chord roots, qualities,
extensions, bass notes, and example voicings.
- **Explore scales**\
Tap the scale-degree strip to browse scale tones, keyboard patterns, and
diatonic chords across a wide range of scales.
- **Musically informed chord detection**\
Goes beyond simple note-matching by ranking and resolving ambiguous
interpretations using musical context such as inversions, extensions, upper
structures, and diatonic preference.
- **Ensemble mode**\
When comping with a bassist, switch to Ensemble so rootless voicings are named
as the chords they imply. The keyboard marks the implied root, and shared
chord links preserve the selected playing mode.
- **Ambiguity-aware user interface**\
When multiple interpretations are plausible, WhatChord shows alternative
candidates rather than hiding uncertainty, and lets you tap them to see why
the current chord ranked first.
- **Context-aware spelling**\
Notes and chord symbols are spelled using the current key signature _and_ the
identified chord context, producing appropriate enharmonic spellings.
- **Notation style preferences**\
Choose between text-based and traditional symbolic chord notation conventions
so chord names read naturally to you.
## Research-Backed Key Detection
Automatic key detection is documented as [WhatKey][WHATKEY], a streaming
key-estimation research project with a frozen evaluation protocol, versioned
fixtures, external baselines, dated experiment logs, and a one-shot held-out
evaluation.
[WHATKEY]: https://github.com/EarthmanMuons/whatchord/tree/main/research/whatkey
## Screenshots
Here's WhatChord in action:
<p>
<img
src="docs/site/public/images/theme_modes.webp"
alt="WhatChord identifying a C13#11 chord from the notes C, E, Bb, D, F#, and A, shown in light and dark themes."
style="width: 800px"
>
</p>
## Installation
WhatChord is available to install in several ways. Choose the option that best
fits your platform and update preferences.
### iOS (App Store)
WhatChord is available on the App Store for iPhone and iPad.
<p>
<a href="https://apps.apple.com/us/app/whatchord-midi/id6758409779">
<img
src="docs/site/public/images/Download_on_the_App_Store_Badge_US-UK_RGB_blk_092917.svg"
alt="Download on the App Store"
style="height:60px; width:auto; margin:15px; vertical-align:middle;"
>
</a>
</p>
### Android (Google Play)
WhatChord is available on the Google Play Store for supported Android devices.
<p>
<a href="https://play.google.com/store/apps/details?id=com.earthmanmuons.whatchord">
<img
src="docs/site/public/images/GetItOnGooglePlay_Badge_Web_color_English.svg"
alt="Get it on Google Play"
style="height:60px; width:auto; margin:15px; vertical-align:middle;"
>
</a>
</p>
### Android (GitHub APK)
For advanced users who prefer direct distribution or third-party updater
workflows, WhatChord also publishes **signed Android APKs** with every GitHub
Release.
#### Recommended: Obtanium
[Obtanium](https://obtainium.imranr.dev/) allows you to securely track and
install APK releases directly from GitHub while verifying developer signatures.
**Workflow:**
1. Install Obtanium on your Android device.
2. Add the WhatChord [GitHub repository][REPO] as an _App source URL_.
3. Obtanium will automatically detect new releases and prompt you to update.
4. Verify the APK signature against the published developer key (see below).
[REPO]: https://github.com/EarthmanMuons/whatchord
### Developer Signing Key (Android)
All official Android builds distributed via Google Play and GitHub are signed
with the same developer key. You are encouraged to verify the signing
certificate fingerprint for this key using [AppVerifier] or Android's native
package verification tooling.
**Signing Certificate Fingerprint (SHA-256)**
```
com.earthmanmuons.whatchord
E8:21:56:94:BA:A2:E0:A3:48:E6:97:49:3E:8B:A9:92:94:93:5E:46:DD:17:03:2C:3C:67:F3:63:9F:A1:3E:F8
```
> ⚠️ Do not install builds whose signing key does not match the fingerprint
> published here.
[AppVerifier]: https://github.com/soupslurpr/AppVerifier
## Who Is This For?
WhatChord is particularly useful for:
- Pianists and keyboardists seeking immediate feedback while they play
- Students learning scales, scale degrees, chord construction, extensions,
inversions, and voicings
- Educators demonstrating harmonic concepts, scale harmony, and chord function
in real time
- Composers and improvisers checking or exploring complex harmony
It provides immediate, intelligent feedback whether you play through MIDI, enter
notes manually, or explore harmony in the app. It is **not** intended to replace
formal analysis tools or notation software, but to complement your practice and
exploration.
## Status
WhatChord is under active development. The app is free to use, contains no
advertisements, and does not collect or transmit any personal data. Scoring
heuristics and user interface details may evolve as edge cases and real-world
usage inform improvements.
This is a human-led project built with assistance from AI coding tools. AI tools
may be used as part of the development workflow for exploration, implementation
support, refactoring, testing ideas, and review, while real people remain
responsible for design decisions, validation, maintenance, and project
direction. The project is developed with deliberate attention to musical
correctness, accessibility, cross-platform behavior, and long-term
maintainability.
If you believe a chord has been identified incorrectly, please [open an
issue][ISSUE] on the GitHub repository. When possible, include the notes you
played, the key signature, and the chord WhatChord reported versus the expected
result. Sharing this data helps debug edge cases and improve the engine.
You can long-press the chord card to open Analysis Details and collect
diagnostic information for a report.
[ISSUE]: https://github.com/EarthmanMuons/whatchord/issues/new/choose
---
Apple, the Apple logo, and App Store are trademarks of Apple Inc., registered in
the U.S. and other countries and regions.
Google Play and the Google Play logo are trademarks of Google LLC.
## License
WhatChord is released under the [Zero Clause BSD License](LICENSE) (SPDX: 0BSD).
Copyright © 2025–2026 [Aaron Bull Schaefer][EMAIL] and contributors
[EMAIL]: mailto:aaron@elasticdog.com