Updated on: May 27, 2025

What is SignalR?

SignalR is a real-time communication library from Microsoft for ASP.NET Core. It allows server-side code to push content to connected clients instantly using WebSockets, Server-Sent Events, or Long Polling as a fallback.

Official documentation: SignalR Overview – Microsoft Docs

Why Use SignalR in .NET Core?

• Real-time updates without polling
• Built-in support in .NET Core
• Scales well with Azure SignalR Service
• Perfect for chat apps, live dashboards, or gaming

Step-by-Step: SignalR Integration Example in .NET Core

1. Create a new ASP.NET Core Project

dotnet new webapp -n SignalRDemo

2. Install SignalR NuGet Package

dotnet add package Microsoft.AspNetCore.SignalR

3. Create a SignalR Hub

public class ChatHub : Hub
{
    public async Task SendMessage(string user, string message)
    {
        await Clients.All.SendAsync("ReceiveMessage", user, message);
    }
}

4. Register SignalR in Startup.cs

// In Program.cs or Startup.cs depending on your .NET Core version
builder.Services.AddSignalR();

app.MapHub<ChatHub>("/chathub");

5. Add SignalR Client to HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/microsoft-signalr/7.0.5/signalr.min.js"></script>
<script>
    const connection = new signalR.HubConnectionBuilder()
        .withUrl("/chathub")
        .build();

    connection.on("ReceiveMessage", function (user, message) {
        console.log(user + ": " + message);
    });

    connection.start().then(function () {
        connection.invoke("SendMessage", "User1", "Hello from client!");
    });
</script>

Bonus: SignalR with Angular or React

SignalR integrates well with modern JavaScript frameworks. See how to use it with:

• SignalR with TypeScript
• Angular + SignalR Example

Conclusion

Integrating SignalR with .NET Core enables seamless real-time communication in your web apps. With minimal setup, you can create chat systems, real-time notifications, and live dashboards. Try it out in your next project!

FAQs

What protocol does SignalR use?

SignalR prefers WebSockets and falls back to Server-Sent Events or Long Polling.

Is SignalR free?

Yes, SignalR is open-source and free to use. Azure SignalR Service has a free tier and paid plans.

Can I use SignalR in Blazor?

Yes, SignalR is supported in both Blazor Server and Blazor WebAssembly apps.

For more tutorials, visit Microsoft Learn or ASP.NET Core Docs.

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