The FastLED library for colored LED animation on Arduino
WS2812 FX library for Arduino and ESP8266
Cooperative multitasking for Arduino, ESPx, STM32, nRF and more
Cross-platform C++ library for use as a default application framework.
C++ cryptographic library (modern hash functions, ciphers, KDFs)
The serial LCD module using ATmega8 along with easy arduino library.