v3.3 Blue Cat Plug’n Script


Blue Cat Plug’n Script
Blue Cat Plug’n Script

Craft your own effects and instruments

Blue Cat’s Plug’n Script is a scripting plug-in that can be programmed to quickly build custom audio and MIDI effects or virtual instruments, without quitting your favorite DAW software.


With this plug-in, you can write your own effects with very little knowledge about programming: no need to invest time and money to learn all these plug-in formats, they are all supported here already! If you do not care about programming, Blue Cat’s Plug’n Script can also be used as a regular processor with existing scripts or to get someone else to write this very particular effect you have been searching for years and cannot find anywhere.

It is also possible for audio software companies to use this plug-in to quickly prototype algorithms and reduce the time required to develop audio products: writing and testing scripts is lightning fast!

Blue Cat Plug’n Script supports both scripts distributed as source code and pre-compiled binary scripts.

For source scripts, it uses the high-performance AngelScript scripting engine, originally developed for video games, with a JIT compiler that helps to compile scripts into machine code for optimal performance. Starting with version 2, the plug-in also supports native (compiled) code and can load binary scripts built from C or C++ (or any language that can export C functions), using the same interface as the angelscript version.

The syntax of the AngelScript language is close to Java, C#, C++, or JavaScript, making it very easy to learn. It is also convenient to reuse your scripts into native code or integrate code snippets found on the web into your script. Also, switching between angelscript and binary versions of the same script is very easy, requiring very few changes.

The plug-in includes dozens of audio and MIDI processing scripts as well as several virtual instruments and utilities to enhance your workflow. Use them as-is, or alternately, as examples to get started to write your own scripts. Share user scripts in the scripts repository. In addition, the scripts repository includes the factory scripts and native projects for reference.

Note: on Mac, the factory native scripts require Mac OSX 10.7 or newer.

Main Features:

  • Audio and MIDI scripting plug-in.
  • Build your own Audio and MIDI effects or virtual instruments.
  • Simple scripting syntax, using either the AngelScript language (similar to C++, Java or javascript) or C/C++ for native code.
  • Native binary scripts support (compiled C or C++).
  • The user interface adapts to scripts automatically. Build your own using Blue Cat’s KUIML language.
  • Up to 48 input parameters and 32 outputs, with full MIDI and automation control.
  • Use your favorite Integrated Development Environment (IDE) for editing.
  • Integrated JIT (Just In Time) compiler brings optimal performance. However, the scripts are not interpreted but compiled.
  • Includes 55 scripts with source code and 132 presets for sound synthesis, and MIDI FX. In addition, get audio FX (comp, gate, tremolo echo, filters, looper…), waveform generation, file playback/recording, and more.
  • Sidechain input and auxiliary outputs support.
  • Surround support (up to 8 audio channels).

Blue Cat Audio Standards:

  • Available as: Mac-AAX, Mac-AU, Mac-RTAS, Mac-VST, Mac-VST3, Win-AAX, Win-DX, Win-RTAS, Win-VST, Win-VST3, Win x64-AAX, Win x64-DX, Win x64-VST, Win x64-VST3.
  • Native DSP code for optimal performance.
  • Full MIDI control and automation support with silent, zipper-free parameters update, advanced response control, and MIDI Learn.
  • No CPU load on idle. In other words, when the plug-in is fed with silence, the processing smoothly shuts down. To explain, this optimizes the CPU usage of your Digital Audio Workstation.
  • Skinnable and customizable user interface with transparency management.
  • Automation and MIDI output: record output parameters as automation curves or send MIDI CC messages to other plug-ins for powerful side chain effects.
  • Smooth Bypass: activate/deactivate the plug-in with absolutely no noise.
  • Undo/Redo.
  • Full-featured integrated presets manager.
  • Copy/paste the plug-in’s state between instances using the system clipboard.
  • In addition, any sample rate supported.


  • An SSE2-enabled processor (Pentium 4 or newer).
  • Microsoft Windows XP, Vista, Windows 7, 8, or 10.
  • Any DirectX / VST / RTAS / AAX compatible host software (32 or 64 bit).
  • For the standalone application, an ASIO, MME, or WASAPI compatible audio interface (ASIO recommended).

Mac OS X

  • An Intel processor.
  • Mac OS 10.7 through 10.15
  • Any VST / Audio Unit (32/64-bit) / RTAS / AAX compatible application.
  • For the standalone application, a Core Audio compatible audio interface.

V3.3 (2020/06/15)

  • Custom graphics and resource files are now be copied when exporting scripts as independent VST, VST3, AU or AAX plug-ins (SCRIPT_DATA_PATH folder).
  • New version of the KUIML GUI programming language (2.7), with new widgets, new mouse and keyboard events handling features, system script function to execute shell commands and more.
  • New version of the Angelscript Engine (2.34).
  • New high-resolution graphics for knobs.
  • New background mode (“None”) to create entirely custom user interfaces.
  • New icon for the Plug’n Script Application.
  • Reduced disk footprint.
  • Fixed crash in exported VST3 plug-in when using input strings in scripts.
  • Fixed crashes when using build-time script in KUIML widgets.
  • Fixed gui.capture objects that could be exposed twice in KUIML objects.
  • Fixed png or svg images alpha mask not properly loaded (was ignored)
  • Fixed ignore_missing attribute for LOAD_FONT that still triggered an error.
  • Mac application now fully supports dark mode on Mac OS Mojave and newer.
  • Mac: fixed settings panel rendering issues in dark mode on Mac OS Mojave and newer.
  • Mac: Fixed keyboard not responding in registration panel in some host applications (LUNA, Garage Band…).
  • Mac: Fixed demo version that could hang Logic when reloading projects using the plug-in.
  • Mac: fixed Retina scaling issue on buffered widgets in apps built with Mac OS 10.14 SDK and newer.

Blue Cat’s Plug’n Script 3.2

This new version lets you export AAX plug-ins for Pro Tools and Media Composer, encrypt the DSP scripts to protect your code and share any type of data with the user interface.

It also includes a new presets browser, full MIDI support for VST3, KUIML 2.6 GUI programming language, and many other improvements.

How To Create AAX PlugIns For Pro Tools And Media Composer

With Blue Cat Plug'n Script 3.2 you can export audio and MIDI plug-in creations as AAX plugins, which can be used in Avid Media Composer and Pro Tools.