The htmx library now offers a dedicated Server Sent Events (SSE) extension. This allows developers to establish a persistent connection to a server, receiving real-time updates directly within their HTML pages. The extension simplifies the integration of live data feeds, chat applications, and other dynamic content, providing an alternative to WebSockets for uni-directional communication.

This new SSE extension replaces the older, experimental `hx-sse` attribute in previous htmx versions. It uses attributes like `sse-connect` for the server URL and `sse-swap` to specify where received data should be rendered. It also provides built-in reconnection logic with exponential backoff for more robust streams. Developers can easily install it via CDN or npm.

SSE is a lightweight protocol, making it easier to use through proxies and firewalls. The extension also supports triggering HTTP callbacks with the `hx-trigger` attribute. For bi-directional communication, WebSockets remain the better choice. A migration guide is available for users of the older `hx-sse` attribute.

With this extension, htmx continues to simplify web development by focusing on HTML-driven interactions. The addition of SSE capabilities further empowers developers to build responsive and interactive web applications with minimal JavaScript. The demo server included in the htmx-extensions repository is useful for testing SSE connections.