What are CRDTs
CRDT (Conflict-free Replicated Data Types) — a class of data structures that can be updated independently on multiple replicas and merged deterministically without conflict resolution. Foundation of collaborative editors (Notion, Figma, Linear). Types: G-Counter (grow-only), LWW-Set (last-write-wins), RGA (replicated growable array for text). Libraries: Yjs, Automerge.
Below: details, example, related terms, FAQ.
Details
- Commutative: A+B = B+A (operation order irrelevant)
- Associative: (A+B)+C = A+(B+C)
- Idempotent: applying the same update twice = same result
- Vector clocks / Lamport timestamps for ordering
- Use cases: collaborative editing, offline-first, distributed counters
Example
// Yjs collaborative text
const ydoc = new Y.Doc();
const ytext = ydoc.getText('content');
ytext.insert(0, 'Hello');
// Syncs over WebSocket — other users see updateRelated Terms
Learn more
Frequently Asked Questions
CRDT vs Operational Transform?
OT (Google Docs) — server-authoritative, transforms operations. CRDT — peer-to-peer compatible, merges without a server. CRDT wins offline-first.
Performance?
Yjs handles thousands of edits/sec. Automerge is slower but more featureful. Both in production (Linear, Figma).
Do I need it for a simple todo app?
No — overhead. CRDTs make sense for collaborative editing or true offline-first UX.