Realtime pages with Blazor and SignalR in .NET 10

BlazorSignalR is the minimal, textbook version of realtime .NET web: a .NET 10 Blazor Web App (interactive server render mode) plus an explicit SignalR hub, showing the two ways content reaches a page live — server-generated push and user-generated broadcast.

Run it in one command

dotnet run --project BlazorSignalR

Open the Realtime page: every three seconds a hosted service pushes a telemetry reading to every connected browser. Open a second tab and type — every tab receives it. Those are the two directions, and everything else about realtime is elaboration.

The three pieces, and where each lives

• Hubs/NotificationHub.cs — the SignalR hub at /hubs/notifications. It tracks attached clients and relays BroadcastFromUserAsync messages to everyone.
• Services/RealtimeHubBridge.cs — a BackgroundService that keeps the connected-client proxies and broadcasts a TelemetryUpdate every three seconds. Registered once as a singleton and as a hosted service, hub and push loop share a single source of truth.
• Components/Pages/Realtime.razor — an interactive component that wires hubConnection.On<T>(...) handlers and disposes them properly. The classic Blazor realtime bug is a leaked handler after navigation; this page shows the clean pattern.

Beginner notes

Blazor Server already feels "live" (the UI diffs arrive over its own circuit), so why SignalR? Because the circuit is per-user: the moment other users or background processes must update your page, you need a broadcast mechanism, and that is exactly SignalR. For the large, feature-complete version of the same ideas, see the Messenger-style chat article.

Repository: github.com/bobhuang1/BlazorSignalR