An animation of the Overdub mark, playing: a strip of tape runs past a green record head. A wobbly orange strand (you) and a steady blue strand (your agent) are written side by side and cross over each other, taking turns on top.
Overdub is a music studio for you and your agents. You lay down a take: hum it, tap it, play it or say it. Your agent plays over it, you play over that, and every take is signed: warm for you, cool for your agent.
Night Shift, 92 bpm
The mic turns on only when you press the button, and nothing leaves your device.
Every picture here is a screenshot of Overdub as it runs today, open on Night Shift, the first of the twelve songs it ships with. It runs in your browser, on a computer or a phone, with nothing to install.
Free, in your browser. The demo agent runs without a key; bring your own Claude key for the real thing. New here? The guide takes five minutes.
Make it warmer.
lowpass 2.4 kHz, drive +3 dBThe bit that goes da-da-DUM.
E4 ⅛, E4 ⅛, G4 ¼ accentLike a heartbeat, but sad.
kick x..x...., 68 bpm, D minorCan the guitar be wetter?
reverb mix 35%, predelay 20 ms“Warmer” means something a little different to everyone who says it. Your agent asks which one you mean, and always shows the exact change it made.
Somebody has to translate. For years that has been Overdub’s maker, AJ Smith, a musician and computer scientist: the friend who hears an idea and turns it into notes, plugins and knob positions. It is slow, and good ideas fade on the way.
Overdub puts an agent in that chair. You keep your hands on the song, and the agent plays on it, in your words and the DAW’s numbers.
Overdub records first and tidies later. Everything you hum, tap or play is kept in the Takes list, so the idea you hum at 2 a.m. is still there in the morning.
Sing the riff. Pitch tracking writes the notes, and the agent fits them to the key if you ask.
Drum on the desk, the pads or the F J K L keys. Your groove lands on the grid, swing and all.
Plug in a guitar or a MIDI keyboard, or play the computer keys. The Guitar Studio’s pedals and amps come with it.
“Darker.” “Half-time in the bridge.” “Make the chorus lift.” Words are best at steering something that’s already there. The agent makes the change and shows you exactly what it did.
Select a track and press R. The bar before the start marker plays with the click while a numeral over the track counts 4 3 2 1, then whatever you play, tap or hum lands on that track at the bars where you played it. Space stops and keeps the take; ⌘Z takes it back out.
One bar of count-in, two, or none (⇧K). Beside the position a square lands on each beat as you hear it, so you can see the next one coming with the sound off. It goes red while you record.
The loop is the punch range. On a drum track each pass layers into one clip: kick and snare the first time round, hats the second, every hit where you played it.
On keys, a hum or a guitar, each pass is a new take in one folder, and ⌘↑ ⌘↓ pick the one that plays. What was there before is muted under the take, on those bars and nowhere else.
With the song already playing, R waits for the next bar line and counts the beats left in this one. Tempo, meter and the loop wait until the take stops.
Played something without recording? It’s in Sketch’s Takes list, and Put it in the song (⇧R for the newest) places it at the beats where you played it if the song was running, or at the marker.
Its record strip shows a beat ruler with each tap where it lands, and switches each pass between Layer and New take, per track.
Ask for an instrument or an effect that doesn’t exist yet. The agent writes it as a small piece of audio code. The studio checks it before you hear it: it has to compile, never output NaN, stay under control at the ends of its knobs and never leave a note stuck, and its loudness is measured against what went in. Then it gets a face with real knobs, and it’s yours.
YouBuild me a pedal that makes my guitar sound like it’s underwater in a cathedral.
AgentCathedral Below is on the board. A slow pitch wobble for the water, a lowpass that sinks as you turn MURK, two stone rooms you blend with NAVE.
wroteCathedral Below, 4 knobscheckedcompiles, no runaway levelsmeasuredwithin 1 LU of the dry guitarrenderedtwice, the same both times
Overdub renders the mix offline, through the same signal path you hear, and measures it: loudness, peaks, spectrum, key. The agent checks its own work before it asks for your ears, then tells you what it found the way an engineer would: louder than your reference, a bit thick in the low mids.
This is how the Guitar Studio’s presets were leveled: every one within a decibel of −14 LUFS (leads sit a touch hotter), true peak at or below −1 dBFS.
Play Cathedral Below above, and this is what an agent sees.
render_and_measure: waiting for soundWarm is you and cool is your agent. Every note, clip and knob turn records who made it and why, so you can see what changed and take back the agent’s last idea without losing yours. Ask for options and you get two to four takes to audition side by side.
Any knob, fader or pan can move over the song. Its moves live in a lane under its track, and the lanes play the same in the studio, in an export and in the render an agent measures.
E opens a track’s lanes: Level, Pan or any knob. Click to add a point and drag it, or select some bars and pick a shape: Ramp up, Ramp down, Swell, Dip, Hold here or Pulse.
“Fade the pad in over bars 1–4” is one call. The agent writes the lane, then renders and measures the bars at each end, and corrects it once if the level moved the wrong way.
Press R and turn a knob: what your hand does goes into its lane from where you touched it to where you let go, then the lane takes over again with a 200 ms glide.
A knob with a lane turns by itself and says so. Turn it yourself and it says held until you give it Back to the lane.
Turn a knob while the song just plays and it stays where you left it. The toast says what moved, over which bars, and offers Write it into the lane, as if you had recorded it.
The start marker keeps you on the bars you’re working on, and anything that sounds can be stopped from the keyboard.
Plays from the start marker and stops back on it, so you can pick bar 4 and work a part bar by bar. ⇧Space plays on from where it stopped; Home puts the marker back on bar 1.
Mutes the selected clips, even while the song plays. A muted clip is printed in outline with its name struck through, and it plays nowhere: not in the song, an export or a render. Trim to the loop cuts a long take down to the loop’s bars.
All off, from anywhere, even a text field: every note, reverb and delay tail, preview and click, whoever started it.
−90 dBFS within 50 msLets every note go, the ones already on their way to an instrument too. Reverbs and delays ring on for 2 seconds, as on a desk, then fade. With the loop off, the song stops by itself a bar after its last note.
every demo song: −60 dBFS 3.5 s after StopOne JSON file holds the whole song. The buttons, the agent in the studio and agents outside it all change it the same way: small typed edits you can read, undo and replay.
{ "kind": "notes", "by": "you",
"notes": "A3@0:1 C4@1:1 E4@2:2" }Overdub speaks MCP. Claude Code, Claude Desktop or anything else that speaks it gets the same tools as the agent in the studio: open your song, edit it, render it and measure it, while you watch it happen. For now that needs a copy of the studio running on your own computer, and the code isn’t public yet.
get_projectapply_opsrender_and_measuredefine_devicepropose_variationsget_capturehighlightplayundoInstruments and effects are small DSP kernels that run in the audio thread with no clock and seeded randomness. Same input, same output, every time. That rule is for determinism; it is not a security sandbox. Faces are drawn from their knobs, so nobody writes UI to make a pedal.
process(L, R, n, p) {
for (let i = 0; i < n; i++)
L[i] = lp.lp(L[i]);
}What went on the reel lately. All of it is in the studio now, and all of it is signed.
Songs
Night Shift has company, each in another genre; Wake-Up Call, Lobby Bar and Room Service are played on the new instruments. They’re staged: every part was written ahead of time, and one in each is signed by Claude, in cool, so you can hear what a take over the house sounds like.
Instruments
Baby Grand, Rotor Cabinet, Music Stands, Flatwound, Suitcase, Mallet Bag, DI Box, Step Ladder, Brass Rail and Risers: a grand piano, a tonewheel organ, a string section, an electric bass, electric pianos, mallets, a guitar you play from the keys, a polysynth with a ladder filter, a horn section and a choir. Gobo Kit gained 808, 909 and ACOUSTIC+ kits. An instrument with named sounds has a Preset line in the Devices tab: pick one and every knob goes there in one undo step. The agent names the same sounds.
Share
The whole song rides in the link, so Overdub’s servers never see it (whatever you paste it into does; recordings stay home). Whoever opens it listens first; Make it yours keeps a copy that says where it came from, every part still signed by whoever played it. A link can carry devices someone wrote, which are code: they stay off until you press Play them, so play them for people you trust.
Transforms
Humanize, strum, arpeggiate, invert, chords from a melody, fill the gap: in the piano roll’s Transform menu, signed by you. The agent has them too, and when one would rewrite your notes it offers takes instead.
Library
The 31 built-in instruments and effects, and 13 an agent wrote, each with the request that asked for it. Every card shows the check its device passed; play any of them on the page. The Guitar Studio’s pedals and amps live in the studio’s browser.
Provenance
The provenance report: each author’s share of the notes, the devices an agent built and what was asked for, and the story of the edits. Open it from the Song menu; print it to keep a PDF.
Export
DAWproject carries the tracks, notes, audio and mix to Bitwig Studio, Studio One, Cubase and others. Overdub’s own devices go as named placeholders with their settings. WAV, stems and MIDI are there too.
Bench
15 jobs a musician would hand an agent (mix, write, edit, build a device), each scored 0 to 1 by measurement, never by a judge. Same song in, same score out.
Browsers
The studio and this page run in all three. On a phone it plays by touch: tap to play, draw and drag notes with a finger, every tab a tap away.
Overdub grows out of the Guitar Studio in Claw’d-o-Matic, AJ’s browser punk-song maker: 101 pedals, 27 amps, 16 cabinets and 5 mics, all synthesized in the browser, and 156 rigs, each leveled by measurement. They all come with Overdub. A few of the pedals:
