Free Online String Instrument Tuner

This free browser-based string instrument tuner detects the pitch of your instrument in real time using your device's microphone and shows you exactly how sharp or flat you are in cents. It supports guitar (standard E A D G B E tuning), drop D guitar, 4-string bass guitar (E A D G), ukulele (G C E A), violin (G D A E), and cello (C G D A). All pitch detection runs entirely in your browser via the Web Audio API — no audio is ever uploaded or sent to a server. The visual meter shows cents deviation (±50¢) with colour-coded zones: green for in-tune (±5¢), amber for close (±20¢), and red for out of tune. A reference table highlights the nearest string as you play, making it easy to tune string by string.