IconVault's BroadcastChannel playground opens a real named channel: connect, open the page in a second tab, and send messages that arrive instantly in every tab. Ping measures cross-tab round trips, and the leader-election demo runs a genuine bully algorithm over the channel so one tab becomes leader while the rest follow. It is free and runs fully in your browser.

BroadcastChannel is the simplest way for same-origin tabs, windows and iframes to coordinate: no server, no storage events hack. The lab shows the message protocol in the open, explains why the sender never receives its own broadcast, and covers the classic use cases: electing one tab to hold a WebSocket, avoiding duplicate polling, and syncing logout or theme changes across tabs.