Free Online Instrument Tuner Tune your guitar, bass, ukulele, violin, and more with this free online tuner. Use your microphone for instant pitch detection or play reference tones. Supports Guitar, Bass, 5-String Bass, Ukulele, Banjo, Violin, Mandolin. And non-standard tunings like Drop D, Open G, Open D, DADGAD, Half Step Down, Full Step Down, Drop C, Open E, Open A