MassTransit is a free and open-source library that helps you build message-based applications and services in .NET.
MassTransit provides a framework that makes it easy to send and publish messages as well as receiving them. If you've ever had to incorporate a messaging system such as RabbitMQ or Azure Service Bus, you may find yourself, like me, writing wrappers or abstractions around it. With MassTransit, it helps a little that they have provided a framework to do some of the work so that you can focus on sending and consuming messages.
This project is an example on how to use and configure MassTransit to implement message-based applications.
At the time of writing, it supports RabbitMQ and Azure Service Bus.