This is a repository for good Arduino boards and libraries with links.
Arduino IDE Download here
They also produce some good introduction tutorials and content. Don’t forget that there are a lot of example sketches that come with the Arduino IDE and most libraries you install. These can be found under the “File” menu.
List of boards to add to Arduino:
ESP8266 based boards e.g. Node MCU v1.0 & Arduino wifi clone boards
http://arduino.esp8266.com/stable/package_esp8266com_index.json
STM32 based board support
http://dan.drown.org/stm32duino/package_STM32duino_index.json
or
https://github.com/stm32duino/BoardManagerFiles/raw/master/STM32/package_stm_index.json
ESP32 based board support
https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
Additional AVR/Atmel mcu support e.g. ATMEGA1284
https://mcudude.github.io/MightyCore/package_MCUdude_MightyCore_index.json
https://raw.githubusercontent.com/Lauszus/Sanguino/master/package_lauszus_sanguino_index.json
Add be adding these links (each on a new line) to the ‘File > Preferences > Additional boards manager URLs’ input
List of good libraries for Arduino projects:
https://github.com/onetransistor/MediaKeyboard
https://github.com/mathertel/RotaryEncoder
SPIFFS uploader