Bangle.js 2 is an open, hackable smartwatch. With a sunlight-readable always-on screen, 4-week battery life, complete flexibility, and complete control of your data, Bangle.js 2 is a refreshing break from expensive smart watches.

You can install new apps from the web or develop your own using JavaScript. All you need is a Web Browser (Chrome, Edge, or Opera) and you can upload apps or write code to run on your watch wirelessly! Bangle.js is waterproof and comes with Bluetooth Low Energy, GPS, a heart rate monitor, accelerometer, magnetometer, a pressure sensor, and more.

Specifications:

IP67 Waterproof (max 1 meter for 30 minutes) Please note: IP67 does not mean you can wear it while swimming.
Nordic 64MHz nRF52840 ARM Cortex-M4 processor with Bluetooth LE
256kB RAM, 1MB on-chip flash, 8MB external flash
1.3 inch 176x176 always-on 3-bit color LCD display (LPM013M126) with backlight
Full touchscreen (6H hardness glass)
GPS/Glonass receiver
Heart rate monitor
3 Axis Accelerometer
3 Axis Magnetometer
Air Pressure/Temperature sensor
Vibration motor
200mAh battery, 4-week standby time
36mm x 43mm x 12mm watch body, with standard 20mm watch straps
Full SWD debug port on the back of the watch