Online Guitar Tuner — Tune by Microphone

A free chromatic tuner that runs in the browser: allow the microphone and a precision needle shows how far each string is from pitch, string by string, with the target notes of your chosen tuning laid out. Prefer tuning by ear? Every reference tone is a tap away, played on a clean guitar voice.

It knows more than standard tuning — Drop D, Drop C, DADGAD, open G/D/E/C, half- and full-step down, plus bass and ukulele tunings — and the reference pitch is adjustable from A432 to A446 for playing along with recordings that are not quite at concert pitch. Audio is analyzed on your device; nothing you play is uploaded anywhere.