Giusto: Intonation Tuner

■ The tuner
Pitch is estimated with three methods — YIN, probabilistic YIN, and MPM over the normalised square difference — because no single one behaves well across a low bass string, a bowed violin and a wind instrument. Reference A can be moved in 0.1 Hz steps for playing with an ensemble that is not at 440.

24 instrument tunings across six families: guitars, basses, ukuleles, the violin family and more. Drop D, DADGAD, open tunings, five- and six-string basses, baritone and soprano ukulele.

Ten temperaments, not just equal: just intonation in major and minor, Pythagorean, quarter-comma and sixth-comma meantone, Werckmeister III, Kirnberger III, Young, Vallotti. Early music does not sit still on an equal-tempered dial, and this is why.

Nine transposing instruments, so a B♭ clarinet or an E♭ alto reads at written pitch instead of asking you to do the transposition in your head. Four ways of naming notes — letters, solfège, German H, and Japanese ハニホ.

On accuracy: against synthesised tones in unit tests the worst error observed was 0.32 cents. That is a measurement of the detection code, not of your device's microphone or of a room.

■ The metronome
Nine time signatures, and the compound ones carry their accent grouping: 5/8 as 3+2, 7/8 as 2+3+2, 9/8 as 3+3+3, 11/8 as 3+3+3+2, 12/8 as 3+3+3+3. Accents can also be set per beat by hand.

Ten subdivisions: straight eighths, triplets, sixteenths, dotted, swing, quintuplets, sextuplets, gallop and its reverse.

Fifteen click sounds — wood block, claves, rimshot, cowbell, cajón, metal tick, triangle, hi-hat, bell, beep, digital, blip, sine, mechanical, marimba. Enough that you can find one that cuts through your own instrument rather than fighting it.

Two practice tools. The tempo trainer raises the tempo on its own every N bars. Bar muting silences whole bars at a time, which is the fastest way to find out whether the pulse is in you or in the speaker.

Timing is scheduled by sample position rather than by wall clock. Over a simulated 30 minutes the accumulated scheduling error stays at 0.000001 samples. Again, that figure comes from the scheduler's unit test, not from a measurement of an actual audio output.

■ Free
The tuner with guitar standard, four-string bass, soprano ukulele and violin; automatic and string detection; equal temperament. The metronome at 2/4, 3/4, 4/4 and 6/8, with four subdivisions and four click sounds. Today's practice time. No ads.

■ Pro
All 24 tunings, all six detection modes, all ten temperaments, all nine metres, all ten subdivisions, all fifteen click sounds, transposing instruments, the tempo trainer and bar muting.

■ Languages
English, Japanese, German, Spanish, French, Italian, Korean, Portuguese, Simplified and Traditional Chinese — ten, with no missing strings in any of them.