# piano.org

> A piano reference: chords, scales, theory & ear training — interactive keyboard diagrams, audio, and practice tools, maintained by Justin Evans. Every chord, scale, mode, and key explained and playable, no account required.

piano.org covers 18 keys, 43 chord types, 25 scale types, and 126 modes. Each reference page includes an interactive keyboard diagram, audio playback, fingering charts, and staff notation, alongside theory lessons and MIDI-based practice tools. Individual chord, scale, and mode pages live under the hubs below and are linked from them; this file lists the hubs and flagship resources rather than every page.

Last updated: 2026-08-02. Counts current as of this date: 18 keys, 43 chord types, 25 scale types, 126 modes.

## Reference hubs

- [Chords](https://piano.org/chords/): All 43 chord types, each shown in every one of the 18 keys with diagrams, audio, and fingering.
- [Scales](https://piano.org/scales/): All 25 scale types — major, minor, pentatonic, blues, and more — in every key.
- [Modes](https://piano.org/modes/): 126 mode pages, Ionian through Locrian, across all keys.
- [Notes](https://piano.org/notes/): All 88 piano keys named, A0 to C8 — each highlighted on an interactive keyboard with frequency, octave, and enharmonics.
- [Voicings](https://piano.org/voicings/): Rootless and fixed-shape jazz piano voicings — how to arrange chord tones at the keyboard.
- [Chord progressions](https://piano.org/chord-progressions/): Common cadences, ii–V–I, and pop changes with voice-leading explained.
- [Voicings — the grip atlas](https://piano.org/voicings/): The four rootless grips (major-scale, whole-tone, diminished, melodic-minor), each with a machine-verified interpretation table and an interactive bass-walker.
- [Theory](https://piano.org/theory/): Lessons on intervals, chord construction, scales, and harmony.
- [Songs](https://piano.org/songs/): Step-by-step breakdowns of iconic piano pieces — the chords, the technique, and the why.

## Chord progressions (the head-term cluster)

The hub at /chord-progressions/ links 28+ topic pages. Common aliases map as follows: the "axis progression", "four-chord song", or "1-5-6-4" is I–V–vi–IV at [/chord-progressions/i-v-vi-iv/](https://piano.org/chord-progressions/i-v-vi-iv/); the "doo-wop changes", "'50s progression", or "Heart and Soul changes" live at [/chord-progressions/doo-wop/](https://piano.org/chord-progressions/doo-wop/); the "two-five-one" (ii–V–I) is covered at [/chord-progressions/jazz/](https://piano.org/chord-progressions/jazz/); "1-4-5" / three-chord songs at [/chord-progressions/standard-progressions/](https://piano.org/chord-progressions/standard-progressions/); the 12-bar blues at [/chord-progressions/blues/](https://piano.org/chord-progressions/blues/); the Andalusian cadence at [/chord-progressions/flamenco/](https://piano.org/chord-progressions/flamenco/).

- [Printable chart](https://piano.org/chord-progressions/chord-progression-chart/): The diatonic chords of all 12 major and 12 minor keys plus the named progressions — derived from the theory engine, printable to PDF.
- [Songs by progression](https://piano.org/chord-progressions/songs-by-progression/): Well-known songs grouped under the progression each is built on (titles and artists only — never lyrics or melody).
- [Reverse lookup](https://piano.org/chord-progressions/from-chords/c-major-g-major-a-minor-f-major/): "I know the chords — what progression is this?" Swap the chord list in the URL (e.g. /from-chords/a-minor-e-minor-d-major/) for any set; candidate keys and Roman-numeral analysis are computed live.
- Every progression page opens with a one-sentence plain-text answer and carries an interactive player that renders the pattern in any of the 18 keys.

## Browse by key

- [Key pages](https://piano.org/key/c/): Each key's signature, sharps/flats, relatives, chords, scales, and modes. Swap the key in the URL (e.g. /key/g/) for any of the 18 keys.

## Search API (for agents)

- [Search endpoint](https://piano.org/api/search/?q=c%20minor%20chord): Public JSON search over the whole reference. GET /api/search/?q=… returns `{answer?, results:[{route,title,type,why,score}]}` — the same engine the site search box uses, including chord-symbol, note-set ("bb d f ab"), and progression parsing. Rate-limited; no key required. Every reference page also opens with a one-sentence plain-text answer, so landing on a route directly always yields a quotable answer.

## Interactive tools

- [What Am I Playing?](https://piano.org/tools/what-am-i-playing/): Play on MIDI, click, or type and get the name live — notes, intervals, chords with inversions, scales, and modes, with staff notation.
- [Chord Finder](https://piano.org/tools/chord-finder/): Type any chord symbol to see it, hear it, and view it on the keyboard.
- [Practice Room](https://piano.org/tools/practice-room/): Connect a MIDI keyboard and drill chords and scales with real-time feedback that grades your playing.
- [Circle of Fifths](https://piano.org/tools/circle-of-fifths/): An interactive map of every key and how they relate.
- [Placement assessment](https://piano.org/tools/diagnostic/): A short diagnostic that maps your skills across 13 domains and recommends what to practice next.
- [All tools](https://piano.org/tools/): The full set of interactive tools.

## Learn

- [Chord & Scale Mastery](https://piano.org/theory/what-is-a-chord/): Two editorial series, from your first triad through altered chords and exotic scales.
- [Voice leading](https://piano.org/theory/voice-leading/): Why progressions sound smooth — common tones and minimal motion between chords.

## Datasets

- [Public datasets](https://piano.org/datasets/): Downloadable, versioned JSONL datasets of every chord and scale in all 18 keys (notes, pitch classes, and intervals), derived deterministically from the piano.org theory kernel and human-verifiable.
- [Chords dataset (v1)](https://piano.org/data/chords-v1.jsonl): 953 chord records, one JSON object per line.
- [Scales dataset (v1)](https://piano.org/data/scales-v1.jsonl): 306 scale records, one JSON object per line.

## About

- [About piano.org](https://piano.org/about/): What the project is and the approach behind it.
- [Flashcards](https://piano.org/flashcards/): The piano.org flashcard system.

## Optional

- [Sitemap](https://piano.org/sitemap-page/): Full list of pages.
- [Gear](https://piano.org/gear/): Recommended equipment.
- [Contact](https://piano.org/contact/): Get in touch.