Server-Sent Events (SSE)

A lightweight HTTP standard for pushing real-time, unidirectional text streams from servers to web browsers.

SSE streamlines real-time updates by maintaining a single, long-lived HTTP connection (typically via the EventSource API). Unlike WebSockets, it operates over standard HTTP/1.1 or HTTP/2, making it firewall-friendly and easier to scale behind existing Nginx or HAProxy configurations. It handles automatic reconnection and event IDs natively, making it the ideal choice for high-frequency data feeds like stock tickers, Twitter streams, or live sports scores where client-to-server communication is unnecessary.

https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events