ModularSynth, a free modular synthesizer in your browser

Put modules in a rack, patch them with cables and build your own sounds and tracks, right in your web browser. No install, no account, no tracking cookies: everything stays on your device. Works on computers, tablets and phones, in English and in French.

What you can do

• Patch 38 modules: oscillators, filters, envelopes, LFOs, sequencers, effects, a sampler and an audio input.
• Play with your computer keyboard, an on-screen keyboard or one or more MIDI keyboards, with pitch bend, mod wheel and up to 16 voices of polyphony.
• Make loops with the Step Seq, the Trigger Seq drum machine and the Note Grid piano roll (the last two with four pattern pages, the Note Grid down to 1/32 notes).
• Map any knob to your MIDI controller with MIDI learn, and sync the Clock to Ableton Live or any DAW over MIDI clock.
• Save scenes, chain them into a song, record a WAV, and share a patch with a link.
• Place sounds around you with the Spatial module: stereo, binaural headphones or 5.1/7.1 surround.
• Switch to the 3D studio: plug cables, turn knobs and play a 61-key keyboard in a virtual evening studio, with the same patch and the same sound.
• Let an AI build and play patches with you, from Claude Desktop, Claude Code or any MCP client, or with WebMCP in Chrome.
• Start from 27 ready-made presets: pluck bass, polyphonic pad, acid techno, FM bell, West Coast lead, generative ambient…

Learn modular synthesis by ear

The Learn course guides you through five chapters and 23 short exercises: from signal to sound, understanding by playing (voltage, modulation, envelopes, scales, waveforms), a machine that plays by itself, your first track, and a gritty techno loop. Every step tells you what you are about to hear, so you understand what each knob and cable does.

Modules

• Sources: VCO, VCO 2 (hard sync, linear FM), Wavetable, Noise, Sampler, Audio input.
• Filters and dynamics: VCF, Ladder (24 dB/oct), VCA, Mixer, Stereo Mix, Quant, Compressor (sidechain), EQ.
• Control: MIDI→CV, ADSR, LFO, Clock, Step Seq, Trigger Seq, Note Grid, S&H, Slew, Attenuverter, Comparator, Logic, Pad XY.
• Effects: Delay, Reverb, Chorus, Distortion, Wavefolder, Phaser, Ring Mod.
• Space: Spatial (direction, height and distance in stereo, headphones or 5.1/7.1 surround).
• Tools: Scope, Output, Memo.

Documentation

Every module, feature and chapter of the course is explained in the ModularSynth documentation: your first sound, the 3D studio, keyboards and MIDI, the modules, learning modular synthesis and playing with AI.

FAQ

Is ModularSynth free?

Yes. ModularSynth is free, with no account and no ads.

Do I need to install anything?

No. It runs in a modern web browser on a computer, a tablet or a phone.

Can I play it with a MIDI keyboard?

Yes. Plug in a MIDI keyboard to play notes, map knobs with MIDI learn, or use your computer keyboard.

Can I use it with Ableton Live or another DAW?

Yes. Send MIDI from your DAW to the browser (loopMIDI on Windows, IAC bus on Mac); the Clock module can follow the DAW's MIDI clock. Record the sound with a virtual audio output or export a WAV.

I'm a beginner: can I learn modular synthesis with it?

Yes. The Learn course guides you in five chapters, from your first sound to a full track; every step tells you what you are about to hear.

Are my patches private?

Yes. Patches and sounds stay in your browser; nothing is sent to a server.

Can an AI build patches for me?

Yes. Connect Claude Desktop, Claude Code or any MCP client with the free MCP server (npx -y modularsynth-mcp), or use WebMCP in Chrome: the AI adds modules, patches cables, writes sequences and plays them in your tab.