syncingsh

한국어

Real-time collaborative notepad. Share a room code and anyone can edit the same document simultaneously. All data exists only in memory and vanishes when everyone leaves.

Core Concepts

• Ephemeral — No data is stored on a server
• Real-time sync — Yjs CRDT + WebRTC P2P for conflict-free collaboration
• No login required — Anyone can join instantly

Tech Stack

Features

Rooms

• Short alphanumeric room codes (Google Classroom style)
• Join by entering a room code
• Data is destroyed when all participants leave

Editor

• Notion-style WYSIWYG markdown editor
• Real-time co-editing via Yjs CRDT (conflict-free)

Users

• No login — join instantly as a guest
• Nicknames auto-assigned as Guest(random) or user-defined, persisted in localStorage

Presence

• Live display of connected users in the room

Architecture

Browser A ──┐                    ┌── Browser B
            │  WebRTC P2P (Yjs)  │
            └────────────────────┘
                     │
              signaling only
                     │
            ┌────────────────┐
            │ Signaling Server│  ← Hono + WebSocket
            │  (Render.com)  │     y-webrtc protocol
            └────────────────┘

The signaling server only brokers initial WebRTC connections. All document data flows directly between browsers via P2P.

Development

Prerequisites

• Node.js 20+
• Bun

Setup

# Install dependencies
bun install

# Install signaling server dependencies
cd signaling && bun install && cd ..

Running locally

You need two terminals — the signaling server and the SvelteKit dev server:

# Terminal 1: Signaling server (ws://localhost:4444)
bun run signaling

# Terminal 2: SvelteKit dev server (http://localhost:5173)
bun run dev

Open http://localhost:5173, create a room, and open the same URL in another tab to test real-time sync.

Tests

bun run test            # Unit tests (Vitest)
bun run test:e2e        # E2E tests (Playwright)

Build

bun run build       # SvelteKit production build

Deployment

See signaling/README.md for signaling server details.