Mosquitto is an open source implementation of a server for version 3 of the mqtt protocol. IBM have a closed source version of this server, known as Really Small Message Broker (rsmb). The plan is to make this a more or less drop in replacement. From version 1.4, Python bindings are no longer included, but are available separately from the Eclipse paho-mqtt project. Mosquitto was written by Roger Light <roger@atchoo.org>