ggwave
Tiny data-over-sound library
...The library generates and analyzes raw waveforms while allowing applications to choose their own audio capture and playback systems. It supports use cases such as device pairing, offline broadcasting, audio QR codes, authorization, and microcontroller communication. Bindings and examples are available for browsers, Python, Node.js, iOS, Android, Arduino, ESP32, and Raspberry Pi Pico. Command-line, graphical, WebAssembly, and file-based demonstrations are included.