A single board with Atmega 2560 + ESP8266.
Full integration on one board: Mega R3 ATmega2560 and WiFi ESP8266 with memory 32Mb (megabyte)
All of the modules can work together or each separately.
Every module has their own pinout headers.
The convenient solution for the development of new projects requiring Arduino Mega and WiFi
Via USB you can update sketches and firmware for ATmega2560 and for ESP8266. For this onboard have the USB-serial converter CH340G