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.
About
The String Tuner uses your device's microphone to detect the pitch of each string as you play it and shows you how flat or sharp you are relative to the target note. It supports standard guitar (EADGBE), bass (EADG), ukulele (GCEA), violin (GDAE), and cello (CGDA) tunings, plus chromatic tuning for any note.
How to use
- 1 Click Allow when your browser asks for microphone access.
- 2 Select your instrument and tuning from the options.
- 3 Play a string — the tuner shows the detected pitch and how close you are.
- 4 The needle moves left (flat) or right (sharp) relative to the target note.
- 5 Tune the string until the needle is centred on green.
- Does the string tuner work without installing an app?
- Yes. The tuner runs entirely in your browser using the Web Audio API and the getUserMedia microphone API. No app download or installation is needed — just grant microphone permission when prompted and start tuning. It works on mobile browsers (Chrome, Safari) as well as desktop.
- What is standard guitar tuning?
- Standard guitar tuning is E2-A2-D3-G3-B3-E4 from the thickest string (6th) to the thinnest (1st). The reference pitch is A4 = 440 Hz. The tuner detects your string's pitch and compares it to the nearest standard note, showing how many cents flat or sharp you are. A cent is 1/100th of a semitone.
- What is a chromatic tuner and when should I use it?
- A chromatic tuner detects any pitch and shows the nearest note in the chromatic scale, regardless of instrument. Use it for alternate tunings (drop D, open G, DADGAD), unusual instruments, or any situation where you need to tune to a specific note that is not in a preset instrument tuning. The standard instrument tunings are presets built on top of the same chromatic detection engine.