The Arduino Uno WIFI Board with ESP8266.  The Arduino Uno Wi-Fi is the same as an Arduino Uno Rev3 but with an integrated Wi-Fi module! The board is based on the ATmega328P with an ESP8266 Wi-Fi Module integrated (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery to get started.

The ESP8266 Wi-Fi Module is a self contained SoC with integrated TCP/IP protocol stack that can give access to your Wi-Fi network. (Or the device can act as an access point.) One useful feature of Uno Wi-Fi is support for OTA (over-the-air) programming, either for transfer of Arduino sketches or Wi-Fi firmware.

The datasheet of  Arduino UNO WIFI is available here.

Specifications:

1. Arduino (Atmel ATMega328P MCU)
2. ESP8266 built-in module
3. Arduino part
   • MCU – Atmel ATmega328 8-bit AVR MCU @ 16 MHz with 32 KB flash Memory, 2KB SRAM, 1KB EEPROM
   • Digital I/O pins – 14, with 6 PWM and UART
   • Analog Input Pins – 6
   • DC Current per I/0 –  40 mA
   • Misc – Reset button
   • Operating Voltage – 5 V
4. ESP8266 part
   • SoC – Expressif ESP8266EX Tensilica Xtensa LX106 processor @ 80 MHz
   • Storage – 4MB SPI flash
   • Connectivity – 802.11 b/g/n WiFi @ 2.4 GHz, wake up time < 2 ms; Antenna: PCB and IPX
   • Misc – Bootloader button, WiFi LED
   • Operating Voltage – 3.3 V
5. Common specs
   • USB – 1x USB device port
   • Input Voltage – 5-12 V via DC jack, Vin or USB port (5V only)
   • Power Consumption – 130 mA (sleepmode 80 mA)
   • Dimensions – 68.5 x 53 mm
   • Weight – 28 grams

More info & typical usage

Arduino Uno Wi-Fi board will come pre-uploaded with the RestServer sketch that allows you to control the board via your web browser using the URL: http://192.168.240.1/arduino/<digital|analog>/<GPIO>/<ON_OFF|<INPUT_MODE>, where digital or analog let you select the IO type, GPIO the pin number,  ON_OFF is either  1 or 0 for on or off, and INPUT_MODE is either input or output. Some examples:

• /arduino/digital/13/1 – Sets GPIO 13 to high
• /arduino/digital/13 – Reads the value on GPIO 13
• /arduino/analog/2 – Reads Analog pin 2 value
• /arduino/mode/13/input – Set GPIO 13 to input

Packages Include:

1 × Arduino Uno WIFI Board with ESP8266