NodeMCU is an open source IoT platform. It includes firmware which runs on the ESP8266 WiFi SoC from Espressif, and hardware which is based on the ESP-12 module. The term "NodeMcu" by default refers to the filmware rather than the dev kits. The firware ESP8266 uses the Lua scripting language. It is based on the eLua project, and built on the Espressif Non-OS SDK for ESP8266. It uses many open source projects, such as lua-cjson and spiffs.
Wi-Fi Module – ESP-12E module similar to ESP-12 module but with 6 extra GPIOs.
USB – micro USB port for power, programming and debugging
Headers – 2x 2.54mm 15-pin header with access to GPIOs, SPI, UART, ADC, and power pinsMisc – Reset and Flash buttons
Power – 5V via micro USB port
Dimensions – 49 x 24.5 x 13mm
Blinking LED Using ESP8266 NodeMCU Lua Wifi
ESP8266 Fan Control from Webserver Demonstration