MassTransit is
free software
Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...
/
open-source
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...
.NET-based
Enterprise Service Bus
An enterprise service bus (ESB) implements a communication system between mutually interacting software applications in a service-oriented architecture (SOA). It represents a software architecture for distributed computing, and is a special vari ...
(ESB) software that helps
.NET
The .NET platform (pronounced as "''dot net"'') is a free and open-source, managed code, managed computer software framework for Microsoft Windows, Windows, Linux, and macOS operating systems. The project is mainly developed by Microsoft emplo ...
developers route messages over
RabbitMQ
RabbitMQ is an open-source message-broker software (sometimes called message-oriented middleware) that originally implemented the Advanced Message Queuing Protocol (AMQP) and has since been extended with a plug-in architecture to support Str ...
,
Azure Service Bus,
SQS, and
ActiveMQ service busses. It supports multicast, versioning, encryption, sagas, retries, transactions, distributed systems and other features. It uses a "Control Bus" design to coordinate and the
Rete algorithm
The Rete algorithm ( , , rarely , ) is a pattern matching algorithm for implementing rule-based systems. The algorithm was developed to efficiently apply many rules or patterns to many objects, or facts, in a knowledge base. It is used to dete ...
to route. Since it does not include "business monitoring" or a "
business rules engine
A business rules engine is a software system that executes one or more business rules in a runtime production environment. The rules might come from legal regulation ("An employee can be fired for any reason or no reason but not for an illegal r ...
" (and requires programming to implement sagas for orchestration), MassTransit is typically considered to be in the category of "lightweight ESB" software.
The project is led by Microsoft MVP and national conference speaker Chris Patterson ("phatboyg"), who is also the author of the TopShelf project, and is co-authored by Dru Sellers. By February 2021 downloads of the package through
NuGet
NuGet (pronounced "New Get")[And The Winner Is, NuGet](_blank)
haacked ...
passed 26,000 per week.
MassTransit is similar to a commercial offering called NServiceBus, and developers often pick one or the other for their implementation. The similarity is no accident, as the authors note that MassTransit was first built in 2007 as an alternative to NServiceBus, and the projects share the use of some code. Other similar "NuGet" ESB packages include Rebus and Rhino Service Bus.
Transition to Commercial Model
In April 2025, the MassTransit project announced that they are transitioning to a commercial licensing model.
References
{{.NET
.NET software
Message-oriented middleware