The Couchbase Sync Gateway enables secure data synchronization across Couchbase Lite enabled clients, using a new websockets based replication protocol that is more efficient than its HTTP based predecessor. Data Synchronization is critical for offline-first mobile apps, requiring the ability to locally store data and sync it to the cloud securely. The tutorial will demonstrate how to set up the Sync Gateway, configure access control and authorization, and use Live Queries to notify clients of changes. The example app, "User Profile", will be extended to support data sync, allowing users to log in and update their profile information while syncing with a remote Sync Gateway that then syncs it to other devices subject to specified configurations.