To use this free online guitar tuner, simply allow microphone access when prompted by your browser. Once access is granted, play a single open string on your guitar near your device’s microphone. The tuner will automatically identify the note you're playing, show you the exact pitch in hertz, and indicate whether the note is too flat, too sharp, or perfectly in tune. Watch the visual waveform for live feedback and adjust your tuning pegs until the tuner displays your target note as “✓ In Tune.” No app or download needed — it works instantly in your browser.