Chariot MQTT Server is a MQTT 3.1.1 compliant MQTT server. It is capable of providing a functional replacement for MQTT Distributor in larger scale deployments. It can be installed as a virtual machine on a private network or in the cloud via Amazon AWS EC2. It comes with a two hour renewable trial period. It can also be set up with a license key from Cirrus Link to enable it permanently. Chariot MQTT Server provides a web based administration page for enabling and limiting user access to the MQTT server via an Access Control List (ACLs). It supports TLS security and username/password authentication in addition to ACLs for client authorization.
More information including installation instructions can be found in the links below.