We present a new simple Internet of Things (IoT) device that we call “Smart Bottle Cap”, which enables a standard bottle to become a user-controllable liquid pouring system. It consists of a mini vacuum pump to start the liquid flowing, a microcontroller to control the liquid flow, a BLE module to connect it to a smartphone, an accelerometer to detect the tilt angle of the bottle, an LED for drawing the attention of users, and a 3.7 V LiPo battery. The device's novel point is that a flow control mechanism built into a standard bottle cap makes the system suitable for general use and enables it to be easily extended.