Crystal Ball

de.singular.crystalball
by Zapstore _@zapstore.dev

Detects guitar chords and combines them into song sheets.

Republished from GitHub / F-Droid by the Zapstore main account.

Crystal Ball listens to your guitar and tells you what chord you just played. Press Detect single chord, strum, and it names the chord and draws how to fret it — with the chords it nearly picked instead one tap away, and other ways to play the same one further up the neck. Capture a whole part and it becomes a song sheet you can keep, correct and share. Early-stage release — expect rough edges. Feedback and bug reports welcome via Issues. Features: * Detect a chord by ear — press, strum, done. It listens until the answer settles rather than for a fixed time, so a clean open chord resolves in about a third of a second; strumming again restarts it, so a bad take needs no second press. * Ranked alternatives — the best fit is a guess, not ground truth, so the runner-ups sit under it and one tap swaps the page over to any of them. * Chord shapes, not just names — the most idiomatic grip drawn large, plus other voicings walking up the neck. Open shapes are the ones a player expects to see, by name. * Capo-aware — detection is unaffected (the microphone hears the real chord either way), but the shapes are redrawn behind the capo, fret numbers stay as printed on your neck, and anything the capo pushes off the end is dropped rather than offered. Chords can be named by what you hear or by the shape your hands make. * Song sheets — capture a part chord by chord, name it Intro or Chorus, reorder the parts, and read the whole song back as diagrams. Parts can be renamed, chords fixed by hand without playing them again, and the finished sheet shared to any app. * Chord dictionary — look any of 240 chords up by hand, without playing a note. Sixths, ninths, 6/9 and 13ths included. * English and German — pick the app's language without changing the whole phone. German note names (H/B) are a separate switch, since being taught H is not the same as reading German. * Session comforts — System/Light/Dark themes, keep-screen-on, an optional capo prompt at launch, an in-app quick help sheet, and backup/restore for your songs. Preferences persist across launches. Heard: maj, min, 7, maj7, m7, sus2, sus4, across all 12 roots. Drawn: those plus dim, aug, m7b5, dim7, 7sus4, 6, m6, add9, 9, maj9, m9, 6/9 and 13 — yours to look up and write down, though the microphone will not name them. Shapes assume standard tuning (EADGBE). Honest about accuracy: template matching on clean triads is good, and degrades on a boomy room, a badly tuned guitar, or a phone held across the room. It is a practice aid, not ground truth — hence the runner-up row, which is one tap from correcting it. Microphone access is required — listening to your guitar is the whole app. Audio is analysed on the fly and never recorded, stored or sent anywhere; the app has no network permission at all. No ads, no trackers, no network access.

First release: Jul 31, 2026, 2 total releases.

Most recent release: Aug 23, 2026.

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Releases

  • Aug 23, 2026 0.5
    The chord library now goes well past what the microphone can name. - **Thirteen more qualities** — `dim`, `aug`, `m7b5`, `dim7`, `7sus4`, `6`, `m6`, `add9`, `9`, `maj9`, `m9`, `6/9` and `13`, at all twelve roots. 240 chords, up from 84. - Look one up without playing a note, or name one by hand when writing a part down. The chip beside the qualities swaps between the seven the app can hear and the thirteen it can only draw. - **Detection is unchanged** — it still hears the same seven qualities, ranks them the same way, and is as accurate as it was. The extensions are drawn but never scored: several cannot be resolved at all, a C6 and an Am7 being the same four pitch classes. - Following **Settings** from the "screen stays on" notice now lands on the System tab, where that switch is. - Content no longer scrolls up through the menu icon and the wordmark. Full notes in [CHANGELOG.md](https://github.com/mkay/CrystalBall/blob/v0.5/CHANGELOG.md).
  • Jul 31, 2026 0.4
    German, and a couple of things that were only ever in English. • German throughout, with a language picker in Settings → System. • German note names (H/B) as a switch of its own: being taught H is not the same as reading German. • Recent songs in the side panel — the last five you opened or read from. • Settings split into Chords, System and About tabs, with the version and licence on About. • Relicensed to GPL-3.0-only; wordmark and icon are CC BY 4.0.