From Demo to Production: Implementing SSE Notifications at Scale in .NET

Server-Sent Events (SSE) offers a lightweight, one-way communication pattern for real-time notifications—distinct from WebSocket's bidirectional overhead. This guide presents production-tested architecture using thread-safe ConcurrentDictionary and heartbeat mechanisms, enabling .NET developers to scale notification systems that rival commercial solutions like WhatsApp's browser notifications without the complexity of bidirectional protocols.