@jsonjoy.com/json-crdt-repo

A local-first browser client for JSON CRDT documents. Persists documents in the browser (IndexedDB via LevelDB) and synchronizes with a @jsonjoy.com/json-crdt-server instance when online. Supports full offline editing — changes are queued locally and synced automatically when connectivity is restored.

Features

• Offline-first — create and edit documents without a server; changes sync when back online.
• Browser persistence — documents are stored in IndexedDB using browser-level.
• Cross-tab sync — edits in one tab are broadcast to other tabs via BroadcastChannel.
• Pluggable remote — connects to any server implementing the JSON CRDT block protocol (default: the public demo server).
• Undo/Redo — built-in undo/redo stack for editing sessions.
• Session management — EditSession wraps a JSON CRDT Log with automatic flush, sync, and patch tracking.

Getting Started

Installation

npm install @jsonjoy.com/json-crdt-repo

Quick Start

import {JsonCrdtRepo} from '@jsonjoy.com/json-crdt-repo';

// Create a repo that connects to your server
const repo = new JsonCrdtRepo({
  wsUrl: 'wss://my-server.example.com/rx',
});

// Create a new document
const session = repo.make('my-document');

// The session exposes a JSON CRDT model you can edit
console.log(session.model.view());

// Edit the document
session.model.api.obj([]).set({hello: 'world'});

// Changes are automatically persisted locally and synced to the server

Key Classes

| Class | Description | |---|---| | JsonCrdtRepo | Top-level entry point; wires together local storage, remote sync, and session factory | | EditSession | In-memory editing session for a single document; wraps a JSON CRDT Log | | EditSessionFactory | Creates and loads EditSession instances | | LevelLocalRepo | Local persistence layer using LevelDB (IndexedDB in browser) | | DemoServerRemoteHistory | Remote sync implementation using JSON Rx RPC over WebSocket | | PubSubBC | Cross-tab notification via BroadcastChannel |