Top 20 NuGet messaging Packages

A fast and ultra-lightweight (sub-100K) general messaging library and service bus for .NET
Crossroads I/O (libxs) is an open source, high performance transport layer. This package includes compiled versions of the native libxs library for x86 and x64.
SQL based subscription storage for Rhino.ServiceBus.
The Cloud Application Framework & Extensions (CloudFx) is a Swiss Army knife for Windows Azure developers which offers a set of production quality components and building blocks intended to jump-start the implementation of feature-rich, reliable and extensible Windows Azure-based solutions and servi...
This package includes the community version of WebSync Server 3.5.0.8 plus the code from the WebClient example to get started. I use John Moss' WebSync Server Starter Kit 1.0.0.3 and update to WebSync Server 3.5.0.8.
High performace concurrency library for the .Net platform.
The Web Solutions Platform (WSP) event system is a general-purpose distributed publish/subscribe event system designed for high performance and low latency. Publish/subscribe is a common communication pattern though there are many variations to solve different scenario requirements. The event system...
(Obsolete. Use ServiceWire.) A Lightweight Services Library for .NET.
A reliable MSMQ messaging library designed for application integration scenarios. Support for transactions, load balancing, automatic retries, json serialization, and more.
Service bus for cross platform development on iOS, Android, WinRT and Windows
Messages are evenly distributed amongst the namespaces and data centers provided in configuration through a TopicAdapter and then aggregated into an endless loop using a SubscriptionAdapter.
SimpleBroker is a straightforward broker-based implementation of the Observer pattern.
UNOFFICIAL: NetMQ is 100% C# native port of ZeroMQ. NetMQ is lightweight high performance messaging library. This current version is still in alpha phase and not recommended for production usage yet
JustSaying is a light-weight service bus on top of AWS services that allows communication via messaging in a distributed architecture.
Messaging components for cross platform development on Android, iOS and WinRT
CloudServiceTaskHost provides lightweight infrastructure for hosting jobs in an Azure Worker Role.
Reactol provides lightweight infrastructure for producing message reactions.
The goal of canal is to make a simple and accessible pub/sub library that can be easily dropped into any javascript application to allow for easy, efficient, organized, and readable event handling.
C# ZeroMQ wrapper
Wraps RabbitMQ.Client in order to make very easy to work with RabbitMQ hiding to the user all the technical aspects, like connections and channels management and providing a clear interface (IAMQPManager) designed to abstract the RabbitMq implementation of the AMQP protocol. Implements RPC (publis...