ARM mbed Watch

The Wearable Reference Design development kit from ARM® mbed helps startups to speed up product design and development, improving their time to market. Thanks to its modularity, various features can be customised to tailor the device functionality and create families of products. Testing is more realistic with the form factor and quality of a finished product. Evaluate and run field tests without having to carry lab equipment, make critical design decisions or commit to any hardware.

It is completely open-source, any developer can start prototyping right away.