Sync Gateway, a key component of the Couchbase Mobile stack, acts as a secure web gateway facilitating data synchronization and access between Couchbase Lite and Couchbase Server. It supports JSON configuration for specifying replications and allows multiple concurrent replications, including both OneShot and Continuous modes, without persistent storage, making it stateless and adaptable to disruptions. Version 1.3 introduces the ability for inter-instance replication, enabling flexible, uni-directional data flows between Sync Gateway instances that can form the basis of globally distributed systems. This architecture is particularly beneficial for mobile and IoT applications where offline performance is crucial, and standard network routing enhances client connectivity. Conflict resolution is managed through a multiversion concurrency control system, allowing document revisions to form a tree structure, with several methods available for resolving conflicts.