NodeMCU is an open-source firmware and development board that helps you to prototype your IoT product with a few Lua script lines. The development board is based on the ESP8266 WiFi chip with 10 GPIO and 1 ADC input. Each GPIO can be used as PWM, I2C, SPI and 1-Wire. Via the micro USB you can program NodeMCU.
The advanced API for hardware IO uses interactive Lua script which is like Arduino code. The event-driven API for network applications faciliates developers writing code in Nodejs style. It speeds up your IOT application developing process.