INA219 Current Sensor Breakout Board
The INA219 is a clever little chip that allows you to do high-side current monitoring of a circuit up to 26 volts. The beauty of this chip is that it uses I2C to communicate with your MCU of choice, unlike analog alternatives. That means you can plug it directly into the ESP8266. You can also connect up to 16 of them on a single I2C bus thanks to the address select pins.
This breakout board includes a 0.1Ω shunt for detecting the current (which gives up to 3.2A of current sensing depending on chip settings) and footprints for standard 5mm screw terminals should you wish to add them. It comes bundled with both male and female 6 pin headers. The rear of the board has 8 solder jumpers for selecting the I2C address.