Live Preview MCP Server

Version 1.1 (post red-team hardening) — Production-grade Model Context Protocol server that lets any MCP-capable AI assistant start, manage, and embed live application previews in an iframe.

Security Hardening (v1.1)

• No shell injection: Docker and process spawn always use argument arrays (shell: false).

• Safe environment: Only an explicit allow-list of env vars is passed; dangerous keys (NODE_OPTIONS, LD_PRELOAD, etc.) are stripped.

• Symlink-safe path checks: realpathSync before allow-list validation.

• WebSocket rate limiting + per-preview connection caps.

• Process-liveness readiness: readiness probe also verifies the child process is still alive.

• Concurrent preview limit (default 10).

• Docker: CapDrop: ALL, no-new-privileges, non-root user where possible, AutoRemove + startup orphan reaper.

• Stronger log redaction (JWT, AWS keys, GitHub/Slack/OpenAI tokens, etc.).

• Token length increased to 32 random bytes.

Related MCP server: Dynamic Code Executor MCP Server

Features

• MCP Tools: start_preview, stop_preview, get_preview_status, get_preview_logs, list_previews, reload_preview, update_preview_config, share_preview, get_mobile_qr, set_auth_token

• Framework Auto-Detection: Vite, Next.js, CRA, Vue, Angular, Express, static, Expo, Flutter

• HTTP Dashboard + Reverse Proxy with framing headers removed

• Optional Docker, Cloudflare/ngrok tunnels, mobile QR, token auth, Cloud-IDE awareness

Requirements

• Node.js ≥ 18

• Optional: Docker, cloudflared, ngrok

Install & Build

cd live-preview-mcp
npm install
npm run build

Run

node dist/index.js

MCP Client Configuration

{
  "mcpServers": {
    "live-preview": {
      "command": "node",
      "args": ["/absolute/path/to/live-preview-mcp/dist/index.js"],
      "env": {
        "PORT": "9000",
        "ALLOWED_DIRS": "/path/to/projects"
      }
    }
  }
}

License

MIT