fugue.mp4

Fugue CRDT Text Editor

A minimal implementation of the Fugue CRDT (and FugueMax in extension) CRDT for collaborative text editing, built with TypeScript and Vite.

What it does

Independent replicas, each maintain their own document tree. You can type in either editor and merge changes in either direction — the Fugue CRDT guarantees convergence without conflicts.

How it works

• Each character is a node in a tree, identified by a unique (replicaId, counter) pair. (replica = device)
• Inserts attach new nodes relative to a left origin, choosing the left or right subtree to preserve intention.
• Deletes are tombstoned (marked as deleted but kept in the tree) so merges stay consistent.
• Merging replays missing nodes from one replica into the other, sorted by ID to ensure deterministic ordering.

Getting started

npm install
npm run dev

Open the local URL printed by Vite. Type in any text area or create new replicas, then use the merge buttons to sync.