Communication & Background

Peer-to-peer audio, video and data channels.

Bidirectional persistent connection to a server.

Low-latency client-server messaging over HTTP/3.

System notifications from the page.

Server-sent push messages, even when the page is closed.

Defer work until connectivity returns.

Large downloads/uploads that outlive the page.

Periodically refresh content in the background.

Message all same-origin tabs and workers.