3 PCS ESP8266 WIFI Witty Cloud Module

Description:
The ESP8266 Witty Cloud ESP-12F WiFi Module is a powerful WiFi enabled processor in a compact package that incorporates an RGB LED, LDR light sensor and pushbutton for easy stand-alone operation.

Witty Cloud board is one of the cheapest ESP8266 device you can get on the market. It has a microUSB port with USB-Serial interface, which means no soldering! The board also contains an RGB LED and a button, which allows me to use it without a breadboard.
Besides adding WiFi capability, the main claim to fame for the ESP8266 processor over the AVR processor of the standard Arduino is that it has a larger 4 MB of Flash memory and runs at clock speeds of 80 MHz and can sometimes optionally be overclocked to 160 MHz and therefore has a fast processing speed.  
This cheap and small Wifi transciever is the perfect solution for home Automation and IoT applications.

Features:
Microcontroller: ESP-8266 32-bit
Clock Speed: 80 / 160MHz
USB Converter: CH340
USB Connector: Micro USB
Operating Voltage: 3.3V
Flash Memory: 4 MB
Digital I/O: 11
Analog Inputs: 1
Communications: Serial, SPI.  I2C and 1-Wire via software libraries
WiFi: Built-in 802.11 b/g/n
LED: Built-in RGB LED
Light Sensor: Built-in LDR photoresistor
Buttons: Built-in pushbutton
Programming: Compatible with Arduino IDE and NodeMCU