Neuroscript Simulator

Try out Neuroscript in this interactive simulator. Write code, test with sample MIDI events, and see the results instantly—all right here in your browser.

Input EventIdle

NoteCCProgramBendAftertouchClockStartStopContinue

Ch

Note

Vel

Script

Examples…Drop system spamNormalize velocityKeyboard split (3 zones)CC modwheel to cutoffChannel glueTranspose octave up

Output

Click Run to execute

VM State

Run a script to see VM state

Web MIDIUnavailable

In—

Out—

Mirror

Quick Reference

Filterkeep notedrop clock, realtimekeep cc where cc == 1

Transformevent(vel=clamp(vel, 35, 110))transpose(12)12 -> vel

Conditionwhen type == note : sendwhen vel > 100 : drop

Emitemit.cc(74, value)emit.noteOn(60, 100)

Features

• Real WASM engine — Scripts compile and run using the same Neuroscript Rust engine as the desktop app
• Syntax highlighting — Keywords, builtins, note literals, and comments are highlighted in real-time
• Web MIDI bridge — Connect hardware controllers to audition scripts with live MIDI input
• Instant feedback — See compile errors immediately as you type

Building locally?

Run npm run prebuild (or make docs-wasm) inside docs/web to copy the WASM bundle into public/neuroscript-wasm/.

How to Use

1. Write or load a script — Use the editor or select an example from the dropdown
2. Configure a test event — Set the event type, channel, note/CC number, and velocity
3. Click Run — Execute the script and see the transformed output
4. Inspect results — View output events or see if the event was dropped/filtered

Example Scripts

Filter System Messages

# Remove timing noise from MIDI stream
drop clock, start, stop, continue, realtime

Normalize Velocity

# Keep only notes and clamp velocity to a usable range
keep note
event(vel=clamp(vel, 35, 110))

Keyboard Split

# Route low notes to channel 2, high notes to channel 3
drop clock, start, stop, continue, realtime

when type == note and note in C-1..B3 : {
  2 -> ch
  send
}

when type == note and note in C4..G9 : {
  3 -> ch
  send
}

CC Mapping

# Map modwheel (CC1) to filter cutoff (CC74)
when type == cc and cc == 1 : {
  emit.cc(74, value)
  send through
}

Transpose with Velocity Shaping

# Transpose up an octave and shape dynamics
when type == note : {
  event(note=clamp(note + 12, 0, 127))
  event(vel=clamp(scale(vel, 1, 127, 40, 110), 35, 120))
}

Language Quick Reference

Filtering

Statement	Description
keep note	Pass only note events
drop clock, realtime	Remove clock and realtime events
keep cc where cc == 1	Keep only modwheel CC
drop all where ch == 10	Drop all events on channel 10

Transforms

Statement	Description
event(vel=100)	Set velocity to 100
event(note=note + 12)	Transpose up an octave
12 -> vel	Alternative assignment syntax
1 -> ch	Route to channel 1

Conditionals

Statement	Description
when type == note : send	Pass notes through
when vel > 100 : drop	Drop loud notes
when note in C2..B4 : { ... }	Execute block for notes in range

Emit & Send

Statement	Description
send	Output current event (consumes it)
send through	Output current event (continue processing)
emit.cc(74, value)	Emit a new CC event
emit.noteOn(note, vel)	Emit a new note on

Built-in Functions

Function	Description
clamp(x, min, max)	Constrain value to range
scale(x, inMin, inMax, outMin, outMax)	Linear interpolation
wrap(x, min, max)	Wrap value into range
min(a, b)	Minimum of two values
max(a, b)	Maximum of two values
abs(x)	Absolute value

Desktop Testing

For more advanced testing, use the desktop app:

1. Create a route with Virtual Keyboard as the source
2. Add a Script transform to your route
3. Open MIDI Monitor to see output
4. Play notes on the Virtual Keyboard
5. Iterate on your script

Next Steps

• Script Engine Overview — Learn scripting fundamentals
• Event Model — Understanding MIDI events in Neuroscript