Quickly prototype your subscriber client with MIMIC and a public MQTT broker

The public MQTT brokers at

http://moxd.io/2015/10/public-mqtt-brokers/

allow you quickly to test your MQTT clients.

By using simulated sensors with MIMIC MQTT Simulator, you can
rapidly prototype your MQTT subscriber application to scale your
IoT environment. For example, this screenshot shows 100 simulated
sensors publishing arbitrary payload messages at predefined rate,
and a mosquitto subscriber client displaying them.