We will be deploying a new feature to our MQTT broker tomorrow morning. We will start broadcasting the current time in two formats at time/ISO-8601 and time/seconds at one second intervals. This should allow users to easily keep track of the current time from devices without real time clocks.

Here are a couple examples of the payloads:

ISO-8601:

topic: time/ISO-8601
payload: 2016-06-01T21:34:12.629Z

Seconds since Unix epoch:

topic: time/seconds
payload: 1464816851