Real-time bi-directional communications between devices, browsers, desktops and servers

WebSocket messaging awesomeness

PowerWebSockets is a high-throughput, cross-platform, full-duplex communication framework in C# that shines at pushing real-time data over a large number of connections between devices, browsers, desktops and servers.

Truly bi-directional


PowerWebSockets offers you full-duplex channels over a single TCP connection using the WebSocket protocol as transport.

Simultaneous sending and receiving

Once one side establishes a channel with another side, both sides can send text or binary data to each other whenever they like, with each side being capable of sending and receiving data simultaneously.

Always available

Bi-directionality is always available without requiring you to establish a TCP connection from both sides or to poll the other side for new messages.

Top performance

Full-scale asynchronous design

PowerWebSockets' full-scale use of asynchronous I/O makes it capable of performing massive operations with minimal memory use, enabling you to push millions of messages per second even on moderate hardware.

Adaptive resource management

The resource use of PowerWebSockets scales up and down dynamically depending on the amount of concurrent activities rather than the amount of connections.

Whether you are sending waves of small messages, streaming big data or broadcasting to thousands of subscribers, the adaptive resource management of PowerWebSockets delivers excellent scalability.

Performance level 100%

Ultra-fast transport compression

To achieve the highest throughput and lowest bandwidth consumption, the compression schemes of PowerWebSockets are specially designed for maximum efficiency with the WebSocket transport while conforming to its "per-message" compression specification.

To improve performance even more, PowerWebSockets incorporates the ultra-fast DEFLATE and LZF4 implementations of DotNetCompression that can further improve scalability with medium-to-large payloads by minimizing the processing overhead required to compress/decompress.

You can set PowerWebSockets to automatically select the compression scheme or you can specify the compression scheme you prefer. Whichever compression scheme you select, it will be transparently negotiated between the communicating sides and your application will remain interoperable with any other WebSocket client or server even if the remote endpoint does not support compression.

High throughput mechanisms


Push-to-All is an out-of-the-box mechanism for quickly pushing a single one-way message or a batch of one-way messages to groups of channels connected to a WebSocketService. Sending messages to a large number of channels is as fast as sending them to one channel.

Server applications can broadcast to any clients that are connected to them, client applications can broadcast to any of the servers to which they are connected, and applications acting both as client and as server can broadcast to any side.

Transparent Burst Messaging

Transparent Burst Messaging

When multiple messages are being broadcasted or sent asynchronously one after the other in quick succession, the WebSocketChannel groups them in batches to increase message throughput by sending them together in a single burst. Creating batches is performed without delaying the outbound queue or increasing the use of memory resources.

The Transparent Burst Messaging mechanism of PowerWebSockets takes care of everything automatically, but if you wish you can prepare and send your own batches of messages.

Lightweight JSON messaging

JSON's format simplicity and WebSocket's communication advantages are combined in a powerful communication framework for building real-time Internet applications and services.

The Lightweight JSON Messaging system

PowerWebSockets offers you two APIs:

  • The basic API that provides the low-level control with which you can build your own messaging system using your favorite format.
  • The Lightweight JSON Messaging system (LiteJM) that uses the JSON format and is ready to use out-of-the-box.

This section highlights the LiteJM features.

Easy service contract definition

To define your service contract you annotate methods with .NET attributes, similarly to the WCF service contract definition. Any class can act as a LiteJM service. You can use the familiar RPC approach in building your applications.

interface IHelloWorld
   string Hello(string message);
   string Goodbye();

One-Way, Request/Response, Faults

You can use all classic types of remote operations including One-Way, Request/Response and Fault messages. In addition to the usual RPC operations, it provides asynchronous streaming and Push-to-All messaging. All operations can be performed both synchronously and asynchronously, except of Push-to-All broadcasts which are always performed asynchronously.

Concurrent operations

Your application can simultaneously make multiple outstanding requests to the remote endpoint through a single channel.

LiteJM provides asynchronous patterns for calling remote operations, enabling your application to send the next request before receiving responses to previous requests. This allows you to increase the number of concurrent operations without creating extra connections.

Utilize the transport's full-duplexity

One-way and request/response operations can be made in both directions of a connection.

PowerWebSockets does not differentiate between client and server sides as its LiteJM service has the same API and the same capabilities on both ends of a network connection. The only difference is in who connects to whom. Once a connection is established, your side does not matter.

Use JSON polymorphism

The JSON serialization of LiteJM can optionally preserve the .NET type information, allowing you to use polymorphism when performing a remote operation invocation.

Push messages to thousands of channels in a snap

Your PowerWebSockets service can push one-way messages to a large number of channels concurrently by performing only one message serialization, resulting in huge savings of processing and memory resources. Quickly sending a message to thousands of channels is as easy as sending it to one channel.

Create and manage groups of channels

The ability of PowerWebSockets to associate each connected client or server with a single or to multiple WebSocketService instances enables you to create and manage groups of channels in order to push different messages to different groups. Push-to-All provides you the fundamentals you need to implement your own Publish/Subscribe or Peer-to-Peer architecture.

LiteJM for WCF

The Lightweight JSON Messaging of PowerWebSockets is also available as a JSON message encoding binding element for WCF, enabling you to use LiteJM not only in your PWS-to-PWS communications but also in your PWS-to-WCF communications.

Send binary streams as message attachments

A unique feature of LiteJM is its ability to stream an arbitrary amount of binary data as an attachment to a JSON message. This enables you to combine a parameterized JSON request and high-throughput streaming into a single remote operation.

using (var fileStream = File.OpenRead("filename.data"))
   client.RequestWithStream("upload", fileStream, "filename.data");
using (var fileStream = File.Create("filename.data"))
   var stream = client.Request<Stream>("download", "filename.data");

Common API at both ends

Common API at both ends

With PowerWebSockets there is little distinction between clients and servers.

The WebSocketChannel

A WebSocketClient initiates a connection, a WebSocketServer accepts the connection, and a WebSocketChannel is established on both sides. The WebSocketChannel represents the full-duplex channel and provides exactly the same functionality at both ends.

The WebSocketService

The PowerWebSockets service API is independent of whether a connection is outbound or inbound, which means that the same instance of the service can act as a server and as a client at the same time. You can even host the same WebSocketService implementation on both the server and the client side.

Streaming for Big Data

PowerWebSockets allows you to transfer messages of arbitrary size, hiding all the complexity of message fragmentation and giving you maximum ease of use.

Intuitive streaming API

The streaming API of PowerWebSockets is very straight forward, representing each inbound or outbound message as a .NET stream. No buffering of the message or its frames is required, allowing you to transfer messages of unlimited size and to accept frames up to 2^64 bytes long while consuming only a few KB of memory.

Buffered or streamed at your choice

Any inbound message can be received either buffered or streamed, irrespective of whether the remote side sent it as a single frame or in a stream of fragments.

Big Data

Easy TLS security

Easy TLS security

Activating TLS is as easy as switching the URI scheme from "ws:" to "wss:" and providing the server's X.509 certificate.

Mutual authentication and username/password authentication

You can use TLS authentication with X.509 certificates to perform server authentication or mutual authentication of both sides. In addition to TLS authentication, you can also perform client authentication using HTTP basic authentication with usernames and passwords.

TLS on Compact Framework, Windows Phone and Silverlight

PowerWebSockets provides TLS security on all supported platforms -- even on platforms on which .NET does not provide TLS streams, including .NET Compact Framework, Windows Phone and Silverlight.

Internet of Things

Get ready for the IoT

The Internet of Things is all about enabling a diverse range of computing devices to communicate over the Internet so that they can provide and consume data and services.

Whether you are writing client-side or server-side software for the IoT, PowerWebSockets is a complete toolkit that includes everything you need: a standard bi-directional prototol, mutual TLS security, DEFLATE and LZF4 compression, Lightweight JSON Messaging, big data streaming, and the scalability required to interconnect a large number of devices.

Use the fridge as a server

Want to create servers running on iOS, Android and Compact Framework devices? Now you can have servers everywhere!

PowerWebSockets-enabled devices are capable not only of establishing full-duplex client connections, but also of accepting connections and providing services to other WebSocket clients.

Internet of Things

What is WebSocket?


WebSocket is a new protocol that represents the next generation of communications across the Web. It enables the creation of event-driven applications that send and receive data at will without polling or page refreshing.

IETF and W3C standardization

WebSocket is part of HTML5, with the IETF standardizing the WebSocket protocol and the W3C standardizing the WebSocket API.

Although WebSocket was initially intended to be used mostly by browser clients, at the IETF its specification was improved to become a universal protocol for efficient, real-time, firewall-friendly communications over the Internet for connecting any type of client to any type of server.

Noemax and HyBi

Noemax has been an active participant and contributor in the Hypertext-Bidirectional (HyBi) working group of the IETF that defined the WebSocket protocol (RFC 6455) and its compression extension.

Specification conformance tests

At Noemax we have a large set of unit, performance and interoperability tests for PowerWebSockets that are run regularly, but we have also tested specification conformance and implementation robustness using the Autobahn|Testsuite for the WebSocket protocol.

Interoperable with all

Web browsers

Did you know that Chrome, Firefox, Internet Explorer, Safari and Opera are WebSocket-enabled and can connect to your PowerWebSockets servers?

With PowerWebSockets you can accept connections from any 3rd party client that supports the WebSocket protocol, including browsers.

And with PowerWebSockets you can also connect to any 3rd party server that supports the WebSocket protocol, including Apache, IIS and Nginx.

Web servers

More features

Advanced keep-alive mechanism

Advanced keep-alive mechanism

Since PowerWebSockets channels may be long-lived, you can use the internal keep-alive mechanism to send pings in order to ensure that your persistent connection remains alive and to verify that the remote endpoint is still responsive. Pongs are returned automatically.

The PowerWebSockets keep-alive mechanism offers multiple modes of exchanging the standard heartbeat control messages, giving you detailed control and enabling you to configure it depending on the type of network infrastructure and the desired level of network error detection.

Integrated tracing

PowerWebSockets provides integrated tracing support that allows you to monitor its activity. A PowerWebSockets application can even be traced remotely by another PowerWebSockets application.

You can configure the TraceSource with any type of trace listeners and then assign the TraceSource property of the WebSocketClient, WebSocketServer, WebSocketEndpoint or WebSocketService objects to the specified trace source in order to log events associated with the object being traced.

Integrated tracting

WCF transport

Looking for a substitute for the aging system-provided net.tcp transport?

Feeling restricted by the system-provided WebSocket implementation whose client side is available only on .NET Framework 4.5+ and its server side only on Windows Server 2012+?

PowerWebSockets includes two binding elements for Windows Communication Foundation clients and severs:

  • A WebSocket transport that uses the high-speed WebSocket implementation of PowerWebSockets which provides wider availability, better performance and more features.
  • A JSON message encoding that enables WCF endpoints to use Lightweight JSON Messaging when communicating with other WCF or PWS endpoints that also use LiteJM and the same transport.

Near-universal availability

The WebSocket transport binding element of PowerWebSockets is available on all platforms supported by PowerWebSockets including all .NET versions from 3.5 onwards, all Xamarin platforms, Windows Phone, Silverlight and Mono -- practically, almost everywhere WCF is available.

Exemplary bi-directional performance

Performance features such as full-scale asynchronous design, adaptive resource management, transparent burst messaging and ultra-fast transport compression are also available in the WebSocket transport binding element of PowerWebSockets.

"Per-message" compression using DEFLATE and LZF4

The WebSocket transport binding element of PowerWebSockets supports the "per-message" compression specification and provides two compression extensions, DEFLATE as per the specification and LZF4 for minimal processing overhead.

LiteJM for WCF clients and servers

The JSON message encoding binding element of PowerWebSockets enables any WCF client or server to communicate using LiteJM with any other WCF or PWS client or server that also uses LiteJM and the same transport.

This message encoding can be used with any WCF transport, but it is recommended to be used primarily with:

  • PowerWebSockets-provided WebSocket transport
  • WCF-Xtensions-provided WebSocket or LiteHTTP transport
  • system-provided WebSocket or HTTP transport

LiteJM features such as duplexity and concurrency work only with WCF transports that support them.


Cross platform

With PWS you can create With PWS you can create



.NET Framework 4, 4.5 and 4.6
.NET Framework 3.5
.NET Compact Framework 3.5
Windows Phone Silverlight 8 and 8.1
Windows Phone 7.1
Silverlight 5



  • Designed for maximum performance
  • 100% managed code, no native code anywhere
  • For Visual Studio and Xamarin Studio projects
  • Royalty-free distribution, no server or runtime fees
  • Subscription model with nightly builds
  • Flexible license permits redistribution by end-users
  • Full source code available with Blueprint add-ons
  • Developer-to-developer support for unlimited issues
  • Assistance with code or configuration
  • On-demand samples and feature requests
  • Perpetual license never expires
  • Access to licensed versions even after subscription


  • Assemblies for .NET Framework 4, 4.5 and 4.6
  • Assemblies for .NET Framework 3.5
  • Assemblies for .NET Compact Framework 3.5
  • Assemblies for Xamarin.iOS
  • Assemblies for Xamarin Android
  • Assemblies for Xamarin.Mac and Mono
  • Assemblies for Windows Phone Silverlight 8 and 8.1
  • Assemblies for Windows Phone 7.1
  • Assemblies for Silverlight 5

Get started today.

Download Now