500+ chord diagrams with audio, a chromatic tuner, and progression builder
C Major
Click individual strings to hear single notes
This Guitar Chord Library & Tuner combines three essential tools every guitarist needs into a single, free, browser-based application. Whether you are a beginner learning your first chords or an experienced player exploring new voicings, everything runs instantly in your browser with zero signup and zero downloads.
The Chord Library covers all 12 root notes across 11 chord types, giving you access to over 130 chord voicings with accurate finger placement diagrams. Each chord is rendered as a clear SVG fretboard diagram showing fret positions, finger numbers (1=index through 4=pinky), open strings, and muted strings. The Strum button uses the Web Audio API to synthesize a realistic plucked-string sound, playing each string with a slight delay for a natural strum feel. You can also click individual strings on the diagram to hear just that note, making it easy to check if you are fretting each string correctly.
The built-in tuner uses your device's microphone and the Web Audio API's AnalyserNode to capture live audio. It then applies an autocorrelation algorithm to the time-domain data, which identifies the fundamental frequency of the sound you are playing. This method is the same technique used by professional hardware tuners and achieves accuracy within approximately 1 cent (1/100th of a semitone) in quiet conditions.
The tuning meter displays your pitch relative to the nearest note. The indicator slides left when you are flat and right when you are sharp. When you are within 5 cents of the target pitch, the meter turns green and displays "In Tune!" The tuner also provides reference tones for all six strings in your selected tuning, so you can tune by ear if you prefer.
Six tuning presets are included: Standard (EADGBE), Drop D, Open G, Open D, Half Step Down, and DADGAD. The chromatic detection works for any tuning or instrument since it simply identifies the nearest note from the 12-tone chromatic scale.
The Progression Builder lets you arrange chords in a sequence and play them back at your chosen BPM. Select a key, pick a preset progression (like the ubiquitous I-V-vi-IV pop progression), or click individual slots to build your own. The player strums each chord at the set tempo with visual highlighting so you can practice keeping time and switching chords smoothly.
Five common presets are included: the I-V-vi-IV pop progression heard in thousands of hit songs, the I-vi-IV-V "50s progression," the ii-V-I jazz turnaround, a classic I-IV-V-I blues with dominant 7th chords, and the i-VI-III-VII minor key progression popular in rock and alternative music. Each preset automatically transposes to your selected key.
When using the tuner, tune in a quiet room and pluck each string firmly, letting it ring out. The algorithm needs a clean, sustained signal to detect pitch accurately. Always tune up to the target pitch rather than down, as this keeps the string tension consistent and prevents slippage. If your strings are new, stretch them first by pulling gently away from the fretboard, then retune several times until they hold pitch.
For chord practice, use the Progression Builder at a slow BPM (70-80) and gradually increase speed as your changes become smooth. The Loop toggle lets you repeat a progression indefinitely, which is ideal for building muscle memory. When learning a new chord shape, click each string individually on the diagram to verify that every note rings out cleanly without buzzing or muting.