Automerge
CRDT library from Ink & Switch / Martin Kleppmann — focus on JSON-like structure with full revision history (for "git for data").
Automerge 2 (2023) rewritten in Rust for 10-100× performance improvement. Includes "Sync Protocol" for p2p replication. Philosophically the "local-first software" movement's flagship library. Trapezium: oriented toward CRDTs as data structures + history rather than performance-first. Competitors: Yjs (faster), Loro, Diamond Types.