Multi-tab

worker-sync-db keeps every open tab on the same origin in sync through a SharedWorker named by your dbName.

How it works

1. Each tab calls createDatabase with the same schema and dbName.
2. Tabs connect to one SharedWorker (when the browser supports it).
3. Local put / delete write to IndexedDB in the worker.
4. The worker broadcasts change events to ports that called subscribe on that collection.

const unsub = db.subscribe('todos', (event) => {
  if (event.type === 'put') {
    // refresh UI with event.doc
  }
});

React: useQuery subscribes for you; useSubscribe exposes the raw stream.

Requirements

Requirement	Why
Same dbName	SharedWorker scope + IndexedDB name
Same schema	Otherwise SchemaMismatch
Same origin	Browser SharedWorker isolation
Active subscribe per tab	Fan-out only to subscribed ports
mode: 'auto' or 'shared'	Dedicated mode is per-tab only

Browser support

• SharedWorker — Chromium and Firefox. Required for cross-tab sync.
• Safari / some WebViews — no SharedWorker. With mode: 'auto', the library falls back to a dedicated worker (no cross-tab sync).

const db = await createDatabase({
  schema,
  dbName: 'my-app',
  mode: 'auto',
  sharedWorker: sharedWorkerUrl,
  dedicatedWorker: dedicatedWorkerUrl,
});

Try it

1. Open the live demo.
2. Duplicate the tab.
3. Add or toggle a todo — the other tab updates immediately.

Troubleshooting

If changes do not appear in another tab, see Troubleshooting. Architecture detail: Architecture.