Calibrate
Show your webcam 1-4 fingers to play your four chords (C, G, Am and F unless you change them). A closed fist or open palm stays silent. Works best with one hand about arm's length from the camera, good lighting on your face and hands.
Guide — play a real song in under a minute
Click ▶ Start camera and allow webcam access. Sit about arm's length away with your hand in view and good light on it.
Choose one of the 100 songs in the song list, or search by title or artist. Its chord order appears as a roadmap, like C → G → Am → F.
One finger plays C, two G, three Am, four F. A fist or an open palm is silent, so you always have somewhere to rest.
Flick your hand down while holding a shape and the chord is strummed again. Do it on the beat.
Press ▶ Start beat for a drum backing. With a song picked, the roadmap lights up the next chord on every bar.
What is in here
C, G, Am and F are the I, V, vi and IV chords of C major. Click any chord under Your 4 Chords to pick another root and type, or tap a quick set such as G D Em C. Song roadmaps follow your choice.
- ☝️ 1 finger
- C major
- ✌️ 2 fingers
- G major
- 🤟 3 fingers
- A minor (Am)
- 🖖 4 fingers
- F major
- Quick sets
- C G Am F · G D Em C · D A Bm G · A E F♯m D · E B C♯m A · F C Dm B♭ · Am Em F G · jazzy 7ths
- ✊ / 🖐️ · 👇
- Fist or open palm is silent · flick down to re-strum
Pick how many hands the camera listens to. Bass + Chords splits the job the way a band does, with a separate sound for each side.
- 1 Hand
- Tracks one hand and ignores a second in frame
- 2 Hands
- Each hand holds its own chord: layer two, or jam with a friend
- Bass + Chords
- Left hand plays the bass root, right hand the chord
All synthesised in the page. The bass is chosen separately, so you can put an upright under a piano or a synth bass under a guitar.
- Chords
- Guitar · Pad · E. Piano · Banjo · Organ · Synth · Bells
- Bass
- Electric · Upright · Synth
- Transpose
- −1 / +1 semitone, up to an octave either way
Each song is listed with its artist and its rotation of the same four chords. The Roman numerals tell you where it starts.
- I-V-vi-IV
- C → G → Am → F, 50 songs
- vi-IV-I-V
- Am → F → C → G, 34 songs
- Others
- I-IV-V-I, I-vi-IV-V, IV-I-V-vi, vi-I-V-IV
- Search
- Filter by title or artist as you type
A 16-step beat machine that loops while you play. Start it, pick a style and set the tempo; nothing to program.
- Styles
- Pop/Rock · Ballad · Latin · EDM
- BPM
- 60 to 160
- 🔊
- Its own volume, separate from the chords
Tracking is best with the whole hand in frame, even light and each shape held clearly for a moment rather than mid-movement.
- Distance
- About arm's length; too close or too far both hurt
- 🪞 Mirror
- Show the camera like a mirror, or as the camera sees it
- ⛶ Fullscreen
- Camera, chord and song roadmap fill the screen
Flicking is fun but hard to keep in time. Pick a strumming pattern above the camera and the chord you hold is played on the beat, with down and up strokes and a gentle bass under it. The beat starts by itself.
- Flick
- You strum, by flicking your hand down (or the Space bar)
- Down 4 · Rock 8ths
- Steady quarter notes · driving eighth notes
- Folk · Pop
- The classic down-down-up-up-down-up · a lighter, syncopated strum
- Reggae
- Short upstroke chops on the off-beats
- Arpeggio
- The chord picked note by note, low to high and back
Pick a song, press 🎯 Follow song and count along: one bar of clicks, then each chord of the song gets one bar. The page checks how long you hold the right chord and gives each bar a verdict.
- Per bar
- Perfect (75% or more) · Good · Close · Miss
- Per run
- ★★★ from 90% · ★★ from 70% · ★ from 45%
- Progress
- Best score per song, day streak, runs this week, kept on this device
- Suggest
- 🎲 picks the next song you have not played or mastered
Every chord card shows how to finger it on a guitar, or which keys to press on a piano. It follows whatever chords you pick and also appears next to the target chord in follow mode.
- 🎸 Guitar
- Open shapes where they exist, barre shapes otherwise
- 🎹 Piano
- The chord's notes lit up on one octave, root in yellow
- Transpose
- Read as a capo: +2 means capo on fret 2
No webcam, a blocked camera, or a phone held in one hand? Choose ⌨ Play with keyboard / touch or turn on the 🎹 Pads. Everything else works the same: songs, strum patterns, follow mode and stars.
- 1 – 4
- Hold C, G, Am, F (or your own four chords)
- Q W E R
- Second hand or bass, in 2 Hands and Bass + Chords modes
- Space · B · Esc
- Strum again · beat on/off · let go of everything
A small meter shows how well your hand is seen and says what to fix. If the count still jumps, raise the steadiness, or calibrate: a fist and an open hand, a second each, and the page sets finger thresholds for your hand.
- Quality
- No hand · Poor · Fair · Good · Great, with a reason
- Steadiness
- How many frames a new finger count must hold
- Calibrate
- Saved on this device, reset any time
Play 100 songs with just 4 chords: C, G, Am and F
The 4 Chord Song Player is a webcam instrument that plays only four chords, controlled with your hand. Raise one to four fingers to choose C, G, Am or F, flick down to strum, and pick a song from a list of 100 to see the order those same four chords come in. You do not need a guitar, a piano or any musical experience. It is a spin-off of Simple Hand Tracking Chords, stripped down so anyone can play along to a real song in under a minute.
Why 4 chords can play 100 different songs
In the key of C, the chords C, G, Am and F are the I, V, vi and IV chords of the scale, and together they form the most recorded chord sequence in pop music. The musical comedy act Axis of Awesome made a running joke of it, but it really is everywhere, from Let It Be to Don't Stop Believin' to modern EDM. What changes from song to song is not the chords but the order they come in.
The label next to each song is that order in Roman numerals, where I = C, IV = F, V = G and vi = Am. I-V-vi-IV cycles C → G → Am → F. vi-IV-I-V starts on Am instead: Am → F → C → G. Same four chords, a different starting point and a different feel. The list is a curated set of well-known songs commonly cited as using this chord family, across pop, rock, country, EDM and film soundtracks.
How to play along
Pick a song and its roadmap appears above the camera. Hold each chord shape and flick down to strum on the beat. The app never streams or plays the original recordings; you play the progression yourself while the drum computer keeps time. It does not ship an exact tempo for each song, so drag the BPM slider (60 to 160) until it feels right, or look up the song's BPM and match it.
Left-hand bass in Bass + Chords mode
In Bass + Chords your left hand stops playing chords and plays the root note of the chord you show, in the bass register and doubled an octave up for body. Flicking down plucks it again, so you can play a bass line in time with the drums while your right hand holds the chord. The roots stay inside a narrow range, C2 to A2, so the line walks between notes instead of leaping an octave when you move to Am. The bass has its own signal path without reverb, which keeps the low end tight.
- Electric: a fingered electric bass with a round fundamental, a little growl and a soft pluck.
- Upright: a darker acoustic double bass with a short decay and a stronger thump.
- Synth: a resonant sub bass whose filter sweeps down on every note.
Seven instrument sounds
Guitar is a bright plucked tone for strumming, Pad a soft sustained sound for slower songs, E. Piano a mellow electric piano, Banjo a short, twangy pluck, Organ a steady drawbar-style tone, Synth a brighter detuned lead and Bells a shimmering tone with a long tail. Switch any time with the buttons above the camera. Transpose moves everything up or down in semitones, so the same finger shapes play in another key.
Follow mode: practise a song and get scored
Choose a song, press 🎯 Follow song and the page gives you one bar of count-in clicks. After that every chord in the song's roadmap lasts one bar, and the target chord, the next one and a progress strip stay on the picture. Throughout each bar the page checks whether the target chord is held, ignoring the first sixteenth notes so you have time to react. The share of the bar you spent on the right chord becomes a verdict: Perfect from 75%, Good from 50%, Close from 25% and Miss below that. A run lasts 1, 2, 4 or 8 rounds of the chord order, and its average gives you up to three stars: ★★★ from 90%, ★★ from 70%, ★ from 45%.
Slow the beat down until the changes feel comfortable, then bring the BPM up over a few runs. Your best score per song, your day streak and the runs of the past week are shown in the Practice panel. They live in your browser's local storage on this device, are never uploaded, and the Reset progress button clears them.
Strumming patterns instead of flicking
Strumming by flicking your hand needs good timing and a steady hand. With a strumming pattern selected the beat does the strumming and you only choose the chord: Down 4 plays one down stroke per beat, Rock 8ths plays eighth notes, Folk plays the classic down-down-up-up-down-up, Pop a lighter syncopated version, Reggae short upstroke chops on the off-beats and Arpeggio picks the notes one after another. Down strokes sweep from the low notes to the high ones, up strokes touch only the top strings and play softer, and in Bass + Chords mode the left hand adds a bass root on the strong beats.
Chord diagrams for guitar and piano
Each of your four chords shows a diagram. The guitar view uses the usual open shapes for the common chords (C, G, Am, F, D, Em and many sevenths) and works out a playable shape with at most four fingers for the rest, with the root in the bass. The piano view highlights the notes of the chord on a single octave. When you transpose, read the guitar shapes as a capo: transposed up by 2 semitones means a capo on fret 2.
Playing without a webcam
The camera is optional. Press ⌨ Play with keyboard / touch on the start screen, or switch on the chord pads. Hold 1 to 4 for the four chords, Q W E R for the left hand or bass, Space to strum again, B to start or stop the beat. The pads accept several fingers at once, so a phone or tablet works too. The keys use their physical position, so they work on AZERTY and QWERTZ keyboards as well.
Better hand tracking: quality meter, steadiness and calibration
While the camera runs, a small meter shows whether your hand is seen well and why not: too small in the picture, too close, dropping out, or finger count jumping around. The steadiness setting decides how many frames a new finger count must hold before the chord changes, which removes most accidental chords between two shapes. If your fingers are still misread, run the calibration: make a fist, then open your hand wide, a second each. The page measures how far each finger stretches in both poses and stores the midpoint as your own threshold for that finger, on this device only.
How the hand tracking works, and your privacy
The app uses Google's MediaPipe hand-landmark model, running in your browser through WebAssembly, to find 21 points on each hand in the webcam image. It counts the extended fingers and maps that count straight to a chord: no calibration needed (an optional five-second one is there if your fingers get misread) and nothing to wear or install. The whole pipeline runs in this tab, so your video is never uploaded, recorded or saved, and closing the tab discards it. Your settings, your finger calibration and your practice progress are kept in your browser's local storage (the keys fcsp-v1 and fcsp-progress) and never leave this device. The hand model and its code are fetched from jsDelivr and Google storage when you start the camera. It is free, with no account and no ads.
Camera, sound and phone tips
You need an up-to-date Chrome, Edge, Safari or Firefox on a secure https:// page, and you have to allow camera access when asked. If you blocked it by accident, click the camera icon in the address bar, allow the site and reload. Browsers do not start audio until you interact with the page; clicking ▶ Start camera takes care of that, so if it is still silent check your system volume and that the tab is not muted. It works on a phone with a reasonably modern browser, but a laptop webcam with your hand held further away usually tracks more reliably than a phone held in one hand.
More hand-tracking and chord tools
For more chords, try the full 20-chord Simple Hand Tracking Chords. The Hand Tracking Instrument has five play modes including air drums. See real fretboard and piano shapes for C, G, Am and F in the chord chart generator, tune up with the guitar tuner, or play these progressions on pads in the chord pad with drums.