Notion’s production CRDT for collaborative rich text

Notion describes the CRDT/data-model redesign it deployed in July 2025 for concurrent editing and Offline Mode: an RGA-derived sequence structure with stable session/Lamport IDs, tombstones, Peritext-style rich-text annotations, and a text-slice/tree model that preserves edits across concurrent block splits. A search-label index limits the number of blocks fetched when a text instance has been split repeatedly. Notion says the system processes millions of CRDT operations per minute.

https://www.notion.com/blog/how-notion-handles-concurrent-editing-with-crdts