VST Plugin SDK (Delphi)

ZynAddSubFX free software-synthesizer by paulnasca 2

VST Plugin SDK (Delphi) is a free development tool plugin developed by axiworld. Compatible OS(s): Windows .

This is the Delphi translation of the VST 2.4 and VST 3.5 SDKs. It contains everything you need to compile a VST effect or instrument plugin, but not all the examples in the original SDK.


VST Plugin Analyser

VST Plugin Analyser free development-tool by Christian Budde

VST Plugin Analyser is a free development tool plugin developed by Christian Budde. Compatible OS(s): Windows.

VST Plugin Analyser is a measurement tool for VST Plugins. It can be used by plugin developers for debugging and as a quality control tool, since it can work with virtually any sample rate and any VST Host settings. Furthermore several automated tests are included.

A simple interface makes it easy to use for anyone. Predefined measurements allow to measure the impulse response and thus the magnitude and phase response of any VST effect plugin. Different excitation signals also allow to get an overview how non-linearities affect the impulse response. For further nonlinear investigations, a dedicated waveshaper measurement is available. Beside that, a complete suite of unique measurements for dynamics (compressor/limiters) is available.

The measurement results can be saved in several formats. Impulse responses, can be saved as WAV or CSV (for import in to Excel). All plots can be stored as Bitmap/PNG or SVG (only available on request). Furthermore it is possible to copy the measured data to MATLAB for further processing.


  • Fully customisable VST host.
  • Can work faster than real time, allowing to present results instantly.
  • Works virtually with any given sample rate.
  • Every VST parameter is adjustable without using the GUI.
  • Several built-in measurements such as:
    • Impulse Response Measurement (including magnitude and phase response).
    • Harmonic Distortion (including THD, THD+N values).
    • CPU Performance Test (including P4-bug check).
    • Harmonic Response (fast frequency response measurement of K2, K3…).
    • Waveshaper measurement.
    • Several dynamic measurements (e.g. static characteristic, attack/release time, etc.).
    • Built-in generator for white and pink noise.
    • Workbench for virtually every test available (on request).
  • Plots can be saved as WAV, CSV, BMP/PNG and SVG (on request).
  • Special KVR export available to produce graphics optimized for the KVR-Forum.
  • Data can be transferred to MATLAB for further processing.
  • (Last) settings are stored in an INI file.


VST Audio Plug-ins SDK (C++)

VST Audio Plug-ins SDK (C++) free development-tool | wrapper by Steinberg

VST Audio Plug-ins SDK (C++) is a free development tool and wrapper VST, VST3, Audio Unit, AAX plugin developed by Steinberg. Compatible OS(s): Windows 64b, macOS.

Virtual Studio Technology (VST) is developed by Steinberg and first launched in 1996. The SDK/API is freely available to all.

VST creates a full, professional studio environment on your PC or Mac. VST allows the integration of virtual effect processors and instruments into your digital audio environment. These can be software recreations of hardware effect units and instruments or new creative effect components in your VST system. All are integrated seamlessly into VST compatible host applications. These VST modules have the sound quality of the best hardware units, yet are far more flexible. All functions of a VST effect processor or instrument are directly controllable and automatable; either with a mouse or with an external hardware controller. VST also allows easy integration of external equipment, allowing you to put together a system tailor-made to your needs.

Being an open standard, the possibilities offered by VST have steadily been growing over the past decade. New virtual effect processors and virtual instruments are constantly being developed.

VST 3 is a general rework of the long-serving VST Plug-in interface. It is not compatible with the older VST versions, but it includes some new features and possibilities. We have redesigned the API to make it not only far easier and more reliable for developers to work with, but have also provided completely new possibilities for Plug-ins. These include:

  • Improved Performance with the Silence Flag

Processing can optionally be applied to Plug-ins only when audio signals are present on their respective inputs, so VST 3 Plug-ins can apply their processing economically and only when it is needed:

  • Multiple Dynamic I/Os

VST 3 Plug-ins are no longer limited to a fixed number of inputs and outputs, and their I/O configuration can dynamically adapt to the channel configuration. Side-chains are also very easily realizable. This includes the possibility to deactivate unused buses after loading and even reactivate those when needed. This cleans up the mixer and further helps to reduce CPU load:

  • Sample-accurate automation

VST 3 also features vastly improved parameter automation with sample accuracy and support for ramped automation data, allowing completely accurate and rapid parameter automation changes:

  • Logical Parameter Organization

The Plug-in parameters are displayed in a tree structure. Parameters are grouped into sections which represent the structure of the Plug-in. Plug-ins can communicate their internal structure for the purpose of overview, but also for some associated functionality (e.g. program-lists):

  • Resizeable UI editor

VST 3 defines a way to allow resizing of the Plug-in editor by a user:

  • Note Expression

VST 3 defines with Note Expression a new way of event controller editing. The Plug-in is able to break free from the limitations of MIDI controller events by providing access to new VST 3 controller events that circumvent the laws of MIDI and provide articulation information for each individual note (event) in a polyphonic arrangement according to its noteId:

  • Factory Concept

VST 3 Plug-in library could export multiple Plug-ins and in this way replaces the shell concept of VST 2 (kPlugCategShell).

VST is a trademark of Steinberg Media Technologies GmbH, registered in Europe and other countries.



VST-Scanner free development-tool by VB Audio

VST-Scanner is a free development tool plugin developed by VB Audio. Compatible OS(s): Windows.

VST-Scanner allows you to register and test VST plugins.

It consists in two tabs: the “Scan Plugins” section searches for VST plugins and validates them, and the “Test Plugin” section allows you to do a sharp analysis of a particular plugin and to put it in the context of real use to tackle possible problems.


VST 3 Plug-in Development Host

VST 3 Plug-in Development Host free development-tool by Steinberg

VST 3 Plug-in Development Host is a free development tool Stand Alone plugin developed by Steinberg. Compatible OS(s): Windows 64b, macOS.

The VST 3 SDK provides a PluginTestHost application for Mac OS X (Universal Binary) and Window (32-bits, 64-bits).

This application allows you to load a plug-in, simulates some inputs (Audio and Event) and acts like a small VST3 host application based on an ASIO driver. Included in this application is a test module which allows you to check your plug-in regarding VST3 standard.


VST-Plugin Unit Test

VST-Plugin Unit Test free development-tool by Christian Budde

VST-Plugin Unit Test is a free development tool plugin developed by Christian Budde. Compatible OS(s): Windows 64b.

VST-Plugin Unit Test is an ‘Extreme Programming’ unit test for generic VST-Plugins. It is based on DUnit and allows automated tests for a whole collection of plug-ins. It was written to ensure the quality of Christian’s open source project, but might be useful for other plug-in developers as well. A detailed manual explains all tests.



SonicBirth free development-tool by SonicBirth

SonicBirth is a free development tool VST, Audio Unit plugin developed by SonicBirth. Compatible OS(s): Windows.

SonicBirth is an “AudioUnit/VST designing application“. It allows users to build their own AudioUnit/VST plugins, either by working with existing circuits or by creating circuits completely from scratch. SonicBirth is also an AudioUnits package, as it comes bundled with a set of plugins designed for standalone use as plugins as well as pre-constructed circuits to modify or build upon for creating new plugins. Whether you’re looking for traditional eqs, compressors, and reverbs, or softsynths, distortion, and filters, etc., SonicBirth allows you freedom and creativity over your sound.

SonicBirth is based on a powerful, flexible engine. Every plugin can be used in 32 bits or 64 bits for added precision. Since all plugins share this engine, any improvement in speed will benefit all of them.



RenderSkin free studio-tool | development-tools by audioD3CK

RenderSkin is a free studio tools and development tools plugin developed by audioD3CK. Compatible OS(s): Windows, macOS.

RenderSkin is a tool to prepare animation frames like from 3d renderings to be used as an interactive UI. It features an editor to mark regions for interactions and some advanced logic to make the UIs resizable. A JUCE based c++ library is available to use the produced skins in your software.



Protoplug free development-tool by Open Source Audio Research

Protoplug is a free development tool VST, Audio Unit plugin developed by Open Source Audio Research. Compatible OS(s): Windows 64b, macOS, Linux.

Create audio plugins on-the-fly with LuaJIT.

Protoplug is a scriptable plugin that lets you load and edit Lua/LuaJIT scripts as audio effects and instruments. The scripts can process audio and MIDI, display their own interface, and use external libraries.

Cross-platform: builds for Windows, Mac OS X and Linux. This means that all protoplug scripts are compatible with these platforms and can be loaded into a huge amount of audio software (glory to JUCE).

Fast: Use the speed of LuaJIT, and perform DSP tasks as efficiently as old school C implementations.

Free and open source: Want a new feature? Add it yourself. The source is MIT-licensed and available on Github.



NASPRO free development-tool | adapter by NASPRO development team

NASPRO is a free development tool and adapter LV2, DSSI, Ladspa plugin developed by NASPRO development team. Compatible OS(s): Linux.

NASPRO is meant to be a cross-platform sound processing software architecture built around the LV2 plug-in standard.

The goal of the project is to develop a series of tools to make it easy and convenient to use LV2 for sound processing on any (relevant) platform and for everybody: end users, host developers, plugin developers, distributors and scientists/researchers.

This release is a total redesign/rewrite that more or less re-implements the features of the previous release, but in a much cleaner and maintainable way.

It includes:

  • NASPRO core: the portable runtime library at the bottom of the architecture.
  • NASPRO Bridge it: a little helper library to develop insert-your-API-here to LV2 bridges.
  • NASPRO bridges: a collection of bridges to LV2 which, once installed, allow you to use plug-ins developed for other plugin standards in LV2 hosts. In particular, the NASPRO bridges collection includes two bridges: a LADSPA 1.1 and a DSSI 1.0.0/1.1.0 bridge.

All of the code is released under the LGPL 2.1 license.

More information is available on the project’s website.