ESP32 - on Dev Board
esp32_datasheet_en.pdf
esp-wroom-02u_esp-wroom-02d_datasheet_en.pdf
Arduino - ESP32 Github repo
Official Arduino - ESP32 Documentation
Good Wi-Fi info
ESP8266 - on Dev Board
0a-esp8266ex_datasheet_en.pdf
ESP8266-DevKitC_getting_started_guide__EN.pdf