How augur.io uniquely recognise device?

Augur recognize device laptop/pc/tablet a unique id to device (augur.json.consumer.UID). Open Augur and type augur.json.consumer.UID in browser console.

I try opening in different browsers, unique id remains same for each browsers in the same device. I know about fingerprinting, but fingerprinting is browser based.

How it uniquely recognise the device?