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--- title: Azure Relay API overview | Microsoft Docs description: This article provides an overview of available Azure Relay APIs (.NET Standard, .NET Framework, Node.js, etc.) ms.topic: article ms.custom: devx-track-dotnet ms.date: 01/24/2026 --- # Available Relay APIs ## Runtime APIs The following table lists all currently available Relay runtime clients. The [additional information](#additional-information) section contains more information about the status of each runtime library. | Language/Platform | Available feature | Client package | Repository | | --- | --- | --- | --- | | .NET Standard | Hybrid Connections | [Microsoft.Azure.Relay](https://www.nuget.org/packages/Microsoft.Azure.Relay/) | [GitHub](https://github.com/azure/azure-relay-dotnet) | | .NET Framework | Windows Communication Foundation (WCF) Relay | [WindowsAzure.ServiceBus](https://www.nuget.org/packages/WindowsAzure.ServiceBus/) | N/A | | Node | Hybrid Connections | [WebSockets: `hyco-ws`](https://www.npmjs.com/package/hyco-ws)<br/>[WebSockets: `hyco-websocket`](https://www.npmjs.com/package/hyco-websocket)<br/>[HTTP Requests: `hyco-https`](https://www.npmjs.com/package/hyco-https) | [GitHub](https://github.com/Azure/azure-relay-node) | ### Additional information #### .NET The .NET ecosystem has multiple runtimes, hence there are multiple .NET libraries for the Relay. The .NET Standard library can be run using either .NET Core or the .NET Framework, while the .NET Framework library can only be run in a .NET Framework environment. For more information on .NET Frameworks, see [framework versions](/dotnet/articles/standard/frameworks). The .NET Framework library only supports the WCF programming model and relies on a proprietary binary protocol based on the WCF `net.tcp` transport. This protocol and library is maintained for backwards compatibility with existing applications. The .NET Standard library is based on the open protocol definition for the Hybrid Connections Relay that builds on HTTP and WebSockets. The library supports a stream abstraction over WebSockets and a simple request-response API gesture for answering HTTP requests. The [Web API](https://github.com/Azure/azure-relay-dotnet) sample shows how to integrate Hybrid Connections with ASP.NET Core for web services. #### Node.js The Hybrid Connections modules replace or amend existing Node.js modules with alternative implementations that listen on the Azure Relay service instead of the local networking stack. The `hyco-https` module amends and partially overrides the core Node.js modules `http` and `https`, providing an HTTPS listener implementation that is compatible with many existing Node.js modules and applications that rely on these core modules. The `hyco-ws` and `hyco-websocket` modules amend the popular `ws` and `websocket` modules for Node.js, providing alternate listener implementations that enable modules and applications relying on either module to work behind the Hybrid Connections Relay. Details about those modules can be found in the [azure-relay-node](https://github.com/Azure/azure-relay-node) GitHub repository. ## Next steps To learn more about Azure Relay, visit these links: * [What is Azure Relay?](relay-what-is-it.md) * [Relay FAQ](relay-faq.yml)