A collaborative Markdown editor web app - Obsidian's look & feel meets Overleaf's real-time collaboration.

The fastest way to run OverLapis - no Node.js setup required:

git clone https://github.com/morzelowski/overlapis.git
cd overlapis
docker build -t overlapis .
docker run -d -p 4444:4444 overlapis

Open http://localhost:4444 in your browser. Share your IP with collaborators on the same network to edit together in real-time.

Note: The image declares /app/docs as a Docker volume, so your notes survive container restarts automatically. To access files directly from the host, use a bind mount instead:

docker run -p 4444:4444 -v ~/my-notes:/app/docs overlapis

• Real-time collaboration - multiple users edit the same file simultaneously with conflict-free merging (Yjs CRDT)
• Live cursors - see collaborators' cursors and names inline as they type
• Obsidian-style UI - dark theme, file tree sidebar, tabbed editing
• Markdown preview - toggle between editor and rendered preview per file
• Command palette - fuzzy-search and open files (Ctrl+P)
• Persistent storage - files saved as .md on the server filesystem
• Docker support - single container serves both frontend and backend

• Node.js 20+
• npm 10+

# Clone the repo
git clone https://github.com/morzelowski/overlapis.git
cd overlapis

# Install all workspace dependencies
npm install

# Start client (port 5173) and server (port 4444) concurrently
npm run dev

Open http://localhost:5173 in your browser. Open a second tab or window to see real-time collaboration in action.

npm run dev:client   # Vite dev server only (port 5173)
npm run dev:server   # Express/WS server only (port 4444)

npm run build        # Compiles client to client/dist/

overlapis/
├── client/          # React frontend
│   └── src/
│       ├── components/
│       │   ├── Editor/          # CodeMirror 6 editor pane + extensions
│       │   ├── Sidebar/         # File tree
│       │   ├── Tabs/            # Open file tabs
│       │   ├── CommandPalette/  # Fuzzy-search file opener
│       │   └── common/          # Shared UI components
│       ├── hooks/               # YjsContext, useYjs, etc.
│       ├── services/            # API client helpers
│       ├── stores/              # Zustand app store
│       ├── styles/              # CSS custom properties (variables)
│       └── types/               # TypeScript type definitions
├── server/          # Express + WebSocket backend
│   └── src/
│       ├── routes/          # REST API endpoints
│       ├── services/        # Filesystem service (path traversal protection)
│       ├── types/           # TypeScript type definitions
│       └── ws.ts            # y-websocket room handler
├── docs/            # Markdown vault (created at runtime by the server)
├── Dockerfile
└── package.json     # npm workspaces root

Browser A ──┐
            ├──► WebSocket (Yjs / y-websocket) ──► Server ──► docs/ filesystem
Browser B ──┘         (proxied via Vite /ws)

• Each file maps 1:1 to a Yjs room; state is synced between all connected clients.
• REST endpoints (/api/files) handle file CRUD.
• Yjs document content is debounce-written to the docs/ directory on the server.

cd client && npx tsc --noEmit
cd server && npx tsc --noEmit

• @k-Czaplicki - contributions to the project

GNU Affero General Public License v3.0 - free to use, modify, and distribute. If you run a modified version as a network service, you must make the source code available to its users. See LICENSE.md for full terms.