# grooph

> grooph (https://grooph.app) is a free browser metronome and rhythm trainer. Besides a plain click at any tempo and time signature, it plays written rhythms in standard notation, generates random rhythms for sight-reading practice, and can score your timing via a MIDI drum pad or keyboard. It runs in the browser (WebAssembly); no account or installation is needed.

The app draws its whole interface into a single canvas, so the page has no readable text or form controls and cannot be operated through the DOM. Instead, build a link: URL parameters open grooph with a specific rhythm, a generated exercise or a metronome setting (see below).

## Links

Query parameters on https://grooph.app/ (all optional, unknown ones are ignored; also described as OpenAPI at https://grooph.app/openapi.json and listed in the API catalog at https://grooph.app/.well-known/api-catalog):

- `v`: link version; write `v=2`. Without it (version 1), `bpm` counts the meter's beat unit, i.e. eighths in x/8 and sixteenths in x/16, and grooph converts it to quarters.
- `bpm`: tempo in quarter notes per minute, 20-300 (with `v=2`), in every time signature: 7/8 at `bpm=70` plays 140 eighths per minute.
- `r`: a rhythm in the text notation below. Spaces may be written as `+`.
- `ts`: time signature, e.g. `3/4` or `7/8` (1-17 beats over 4, 8 or 16). With `r` it is the default meter; on its own it opens the metronome tab in that meter.
- Generator (a random sight-reading rhythm): `sub` = `8`, `16`, `3` (triplets) or `mix`; `lvl` = complexity 1-5; `bars` = 1-8; `space` = amount of rests 0-1; `seed` = any whole number. The same parameters and seed always give the same rhythm; without a seed every visit draws a new one. Only x/4 time signatures. Do not combine with `r`.
- `swing`: swing feel in percent, 50 (straight) to 75 (dotted); 66 is the triplet feel. `su=16` swings sixteenths instead of eighths.
- `click`: what the metronome clicks in the meter of `ts` (or of the first measure of `r`): one measure in the rhythm notation below, without the time signature. An accented note (`>q`) clicks strong, a plain note medium, a ghost note (`(q)`) soft, a rest not at all. Default: one click per beat group, the first one strong (4/4 has four groups, 6/8 two, 7/8 three: 2+3+2).
- `counter`: a polyrhythm (counter rhythm): a second click the metronome plays against the click of `ts`, with its own sound. One measure in the rhythm notation below, without the time signature, written like `click`. Needs `ts` and works only for the metronome, not together with `r` or the generator. See "Polyrhythms" below for ready-made values.

Examples:

- Metronome, 7/8 with 140 eighths per minute: https://grooph.app/?v=2&bpm=70&ts=7/8
- Written rhythm with a triplet: https://grooph.app/?v=2&bpm=90&r=4/4+q+e+e+t8+t8+t8+r:q+|+q.+e+q+q
- Sixteenth-note sight-reading exercise, level 3, 4 bars: https://grooph.app/?v=2&bpm=80&sub=16&lvl=3&bars=4&seed=42
- Swing click with triplet feel: https://grooph.app/?v=2&bpm=120&ts=4/4&swing=66
- 7/8 click with the middle group silent and the last one soft: https://grooph.app/?v=2&bpm=70&ts=7/8&click=>q+r:q.+(q)
- Metronome in 4/4 with a 3:2 polyrhythm (three clicks against every two beats): https://grooph.app/?v=2&bpm=90&ts=4/4&counter=t4+t4+t4+t4+t4+t4

If the user has unsaved changes, grooph asks before replacing them. Invalid links show an error message that names the problem.

## Polyrhythms

A polyrhythm n:m plays n even counter clicks in the time of m beat units of the meter (quarters in x/4, eighths in x/8), repeated until the bar is full, against the normal click. Pass it as `counter` together with `ts`. Values for common ratios (spaces written as `+`):

| Meter | Ratio | Link |
|-------|-------|------|
| 4/4 | 3:2 | https://grooph.app/?v=2&bpm=90&ts=4/4&counter=t4+t4+t4+t4+t4+t4 |
| 4/4 | 3:4 | https://grooph.app/?v=2&bpm=90&ts=4/4&counter=t2+t2+t2 |
| 4/4 | 5:4 | https://grooph.app/?v=2&bpm=90&ts=4/4&counter=qt4+qt4+qt4+qt4+qt4 |
| 4/4 | 7:4 | https://grooph.app/?v=2&bpm=90&ts=4/4&counter=spt4+spt4+spt4+spt4+spt4+spt4+spt4 |
| 4/4 | 2:1 (also 4:2) | https://grooph.app/?v=2&bpm=90&ts=4/4&counter=e+e+e+e+e+e+e+e |
| 2/4 | 3:2 | https://grooph.app/?v=2&bpm=90&ts=2/4&counter=t4+t4+t4 |
| 3/4 | 2:3 | https://grooph.app/?v=2&bpm=90&ts=3/4&counter=q.+q. |
| 3/4 | 4:3 | https://grooph.app/?v=2&bpm=90&ts=3/4&counter=e.+e.+e.+e. |
| 6/8 | 2:3 (two against each dotted quarter) | https://grooph.app/?v=2&bpm=60&ts=6/8&counter=e.+e.+e.+e. |
| 6/8 | 4:3 | https://grooph.app/?v=2&bpm=60&ts=6/8&counter=s.+s.+s.+s.+s.+s.+s.+s. |

- Any other ratio: write one bar of the meter with n notes evenly spread over every m beats. Use a tuplet when the clicks do not fall on plain note values: `n:m` with the note value of the beat, e.g. in 5/8 seven against five is `counter=7:5e+7:5e+7:5e+7:5e+7:5e+7:5e+7:5e`. Rests fill the gaps between clicks, e.g. 3:5 in 5/4 is `t8 r:t8 r:t8 r:t8 r:t8` three times.
- Ratios with a common factor play like the reduced one: 4:2 in 4/4 is four eighths in the time of two quarters, the same as 2:1, and the app labels such a link 2:1.
- Counter notes click at medium level; `>` makes one strong, `(e)` soft, a rest silences it. Combine with `click` to change the main click as well.

## Rhythm notation

- Tokens are separated by spaces; `|` separates measures (a trailing `|` is fine).
- Durations: `h` half, `q` quarter, `e` eighth, `s` sixteenth, `th` thirty-second; dotted `q.` `e.` `s.`.
- Tuplets (write every note of the group): `t2` `t4` `t8` `t16` `t32` triplets (3 in the time of 2, e.g. `t4` is a quarter-note triplet), `qt4` `qt8` `qt16` quintuplets (5:4), `st8` `st16` sextuplets (6:4), `spt4` `spt8` `spt16` septuplets (7:4), `nt16` nonuplet sixteenths (9:8); over a dotted quarter `qt8_3` (5 eighths in the time of 3) and `spt16_6` (7 sixteenths in the time of 6). Any other ratio is `n:m` plus a note value (`w` `h` `q` `e` `s` `th`), e.g. `7:5e` for seven eighths in the time of five.
- Rest: prefix `r:` (e.g. `r:q`, `r:t8`). Accent: prefix `>` (e.g. `>e`). Ghost (soft) note: parentheses (e.g. `(e)`).
- A time signature such as `3/4` may start a measure; it applies until the next one. Default is 4/4.
- Each measure must add up exactly to its time signature.
- In 4/4: `q q e e q` is quarter, quarter, two eighths, quarter. `s s s s q t8 t8 t8 r:q` is four sixteenths, a quarter, an eighth-note triplet and a quarter rest.

## Features

- Metronome: tempo in BPM, any time signature from 1 to 17 beats over 4, 8 or 16 (e.g. 3/4, 4/4, 5/8, 7/8, 12/8), optional count-in bar, accents, adjustable click sound and volumes per beat type.
- Polyrhythms: the metronome can play a counter rhythm against its click, e.g. 3:2, 3:4, 5:4 or 4:3, or any ratio of one's own; link parameter `counter`.
- Rhythm editor: write a rhythm in standard notation with quarter, eighth, sixteenth and thirty-second notes and rests, dotted notes, accents and tuplets (triplets, quintuplets, sextuplets, septuplets, nonuplets); grooph plays it back with a moving cursor.
- Rhythm generator for sight-reading: random rhythms by subdivision (eighths, sixteenths, triplets or mixed), complexity level 1–5 or a hand-picked set of one-beat groupings, number of bars and amount of rests (x/4 time signatures). Endless mode keeps replacing bars that have already been played.
- Swing feel from straight (50%) to dotted (75%) on eighths or sixteenths; the notation stays straight.
- Counting overlay ("1 e & a", "1 trip let") and optional ghost notes on the free subdivisions.
- Timing accuracy: connect a MIDI device and grooph shows how early or late each hit lands and which notes were missed.
- Pattern library: save and load named rhythms with their tempo (stored locally in the browser).

## How to use

- Play/pause: Space key or the play button. Esc switches between edit and playback mode.
- Share: the library (folder) panel has a "Copy link" button that copies a link to the current rhythm and tempo.
- Generator: open the dice (🎲) menu, choose subdivision, complexity, bars and rests; every change creates a new rhythm.
- Editor: pick a note, rest or tuplet from the palette and click a position in the measure; double-click toggles note/rest.

## Contact

- Feedback and bug reports: hello@grooph.app

## Guides

- [Free Online Metronome](https://grooph.app/metronome/): A free metronome in your browser. Set the tempo from 20 to 300 BPM, pick any time signature, add a count-in or swing, and practice with a clear click.
- [Metronome for Odd Time Signatures](https://grooph.app/metronome/odd-time-signatures/): Practice 5/4, 5/8, 7/8, 9/8 and other odd meters with a free online metronome. Learn the common groupings and hear them with accents.
- [Swing Metronome](https://grooph.app/metronome/swing/): A free online metronome with adjustable swing from straight to dotted feel, for swung eighths or sixteenths. Hear the difference and practice it.
- [Metronome Trainer](https://grooph.app/metronome/trainer/): Practise inner time with bars the metronome leaves out, and build speed with a click that raises the tempo step by step. Free in your browser.
- [Polyrhythm Metronome](https://grooph.app/metronome/polyrhythms/): A free online metronome that plays a polyrhythm against its click: 3:2, 3:4, 5:4, 4:3 or any ratio of your own. Open it with a link.
- [Rhythm Sight-Reading Practice](https://grooph.app/sight-reading/): Free rhythm sight-reading exercises for eighth notes, sixteenth notes and triplets, from easy to hard, played back with a metronome in your browser.
- [Eighth-Note Rhythm Exercises](https://grooph.app/sight-reading/eighth-notes/): Practice reading eighth-note rhythms – quarters, eighths, rests and the first offbeats – with random exercises and a metronome. Free, in your browser.
- [Sixteenth-Note Rhythm Exercises](https://grooph.app/sight-reading/sixteenth-notes/): Random sixteenth-note rhythm exercises in five levels – from four even sixteenths to notes on "e" and "a". Read, count and play along with a metronome.
- [Triplet Rhythm Exercises](https://grooph.app/sight-reading/triplets/): Practice eighth-note triplets with random exercises in five levels – full triplets, rests inside the triplet and offbeat figures. Free with metronome playback.
- [Learn to Count Rhythms](https://grooph.app/learn/): Short guides to counting sixteenth notes, triplets, syncopation and dotted rhythms – with examples you can play back and practice in your browser.
- [How to Count Sixteenth Notes](https://grooph.app/learn/counting-sixteenth-notes/): Learn to count sixteenth notes with "1 e & a" – every common sixteenth-note figure with counting, examples you can hear and exercises to practice.
- [How to Count Triplets](https://grooph.app/learn/counting-triplets/): Learn to count eighth-note triplets with "1 trip let", hear the difference to straight eighths and practice triplets with rests – with playable examples.
- [Syncopation Exercises](https://grooph.app/learn/syncopation/): What syncopation is and how to read it – offbeat eighths, ties across the beat and sixteenth syncopations, with examples you can play and random exercises.
- [Dotted Rhythms](https://grooph.app/learn/dotted-rhythms/): How dotted notes work and how to count dotted quarters, dotted eighths and the dotted "gallop" – with playable examples and practice exercises.
- [Random Rhythm Generator](https://grooph.app/rhythm-generator/): Generate random rhythms in standard notation for sight-reading – eighths, sixteenths, triplets or mixed, five difficulty levels, played back with a metronome.
- [Timing Practice](https://grooph.app/timing-practice/): Tap along, play sticks into the microphone or use a MIDI drum pad and see how early or late every hit is. Free timing practice in your browser.
- [Privacy Policy](https://grooph.app/privacy/): What data the grooph web app and Android app process: no accounts, no tracking, settings stay on your device, microphone audio is analysed locally.