Xsync

Xsync is an open-source cross-platform data synchronization framework and protocol designed to keep data in sync across distributed systems. It enables applications to replicate files, configuration, and application state between devices and services while aiming for eventual consistency and robust conflict resolution.

Design goals include offline operation, modularity, and security. Xsync supports various network topologies, including peer-to-peer and client-server arrangements, and is suitable for environments with intermittent connectivity, ranging from mobile devices to edge services.

Architecture consists of a core synchronization engine, a transport layer that abstracts networking, and pluggable data-model adapters. Conflict resolution is implemented through plug-ins, with options such as CRDT-based convergence and last-writer-wins policies. The system tracks changes using version vectors or causal metadata.

The Xsync protocol defines messages such as SyncInit, DataDelta, and Acknowledgement. Changes are transmitted as compressed deltas, and communication can run over TLS or other secure channels. Authentication and access control are supported via tokens, certificates, or OAuth-like mechanisms.

In practice, Xsync is used by offline-first applications, real-time collaboration tools, distributed caches, and IoT networks to maintain consistency without central bottlenecks.

Several language bindings and reference implementations exist, with community contributions expanding adapters for common storage backends and services.