An Open Source Machine Learning Framework for Everyone

JUCE is an open-source cross-platform C++ application framework for desktop and mobile applications, including VST, VST3, AU, AUv3, LV2 and AAX audio plug-ins.

Cross-Platform C++ GUI Library

Plugin for Neural Amp Modeler

A Collection of Useful C++ Classes for Digital Signal Processing

Audio plugin host

MIDI for Arduino

Element Audio Plugin Host

Teensy Audio Library

This contains all the Airwindows audio open source code

Multi-platform GUI application to effortlessly visualize MIDI activity

Software and hardware platform for simpler building of MIDI controllers.

DISTRHO Plugin Framework

DSP IIR realtime filter library written in C++

A collection of spatial audio related VST/LV2 plug-ins developed using JUCE and the Spatial_Audio_Framework

Official mirror of Rubber Band Library, an audio time-stretching and pitch-shifting library.

A MIDI library over USB, based on PluggableUSB

The Stochas Sequencer

A GUI builder module for JUCE - with examples

ATMega32U4 Arduino board, available from SparkFun Electronics

That's the right number of sines, I think.

Guitar plugin using neural networks to capture real amps and pedals

Arduino library for nRF51822-based Adafruit Bluefruit LE modules

Toptal logo detector

A VST reverb effect in which the reflections can be frozen, filtered, pitch shifted and ultimately disintegrated.

A Java-based (Audio Stream Input/Output) ASIO host.

A bridge between Jack's Transport mechanism and Ableton's Link synchronization.

VST/AU plugin based on the Boomerang+ Phrase Sampler.

Dynamics Processor (Gate, Compressor & Limiter) for the Teensy Audio Library