secure-browser-mcp

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Security-first browser automation MCP server. Built on Playwright with a strict local-only policy.

Security Features

| Feature | Detail | |---------|--------| | Zero telemetry | No data leaves your machine. No PostHog, no analytics, no cloud sync | | Sensitive data masking | Credit card numbers, SSNs, and emails are auto-masked in all tool responses | | No external connections | The server never phones home. Fully air-gappable | | No LLM dependency | No API keys, no AI calls. Your MCP client handles reasoning; this server just drives the browser | | No Python required | Pure Node.js. No Python runtime, no pip, no venv |

Why not @playwright/mcp?

| | secure-browser-mcp | @playwright/mcp | |---|---|---| | Telemetry | None | None* | | Sensitive data masking | Built-in (CC, SSN, email) | No | | External connections | Zero | Depends on config | | DOM element stability | data-mcp-index (CSS-independent) | Accessibility snapshots | | Dependencies | Minimal (Playwright + MCP SDK) | Playwright + MCP SDK |

* @playwright/mcp itself has no telemetry, but does not mask sensitive data in responses passed to LLMs.

Quick Start

Install

git clone https://github.com/aliksir/secure-browser-mcp.git
cd secure-browser-mcp
npm install
npx playwright install chromium
npm run build

Configure

Add to your Claude Code MCP settings (~/.claude/settings.json):

{
  "mcpServers": {
    "secure-browser": {
      "command": "node",
      "args": ["/path/to/secure-browser-mcp/dist/index.js"],
      "env": {
        "BROWSER_HEADLESS": "true"
      }
    }
  }
}

Set BROWSER_HEADLESS to "false" to see the browser window.

Available Tools

| Tool | Description | |------|-------------| | browser_navigate | Navigate to a URL (supports new_tab) | | browser_get_state | Get page state with indexed interactive elements | | browser_click | Click by element index or coordinates | | browser_type | Type text into an element (sensitive data auto-masked) | | browser_screenshot | Take a screenshot (viewport or full page) | | browser_scroll | Scroll up or down (80% of viewport) | | browser_go_back | Navigate back in history | | browser_get_html | Get HTML content (full page or CSS selector) | | browser_list_tabs | List all open tabs | | browser_switch_tab | Switch to a tab by ID | | browser_close_tab | Close a tab by ID | | browser_list_sessions | List active browser sessions | | browser_close_session | Close a specific session | | browser_close_all | Close all sessions and browsers |

How Masking Works

When browser_type or browser_get_state processes text, patterns are automatically replaced before the response reaches your MCP client:

| Pattern | Masked as | |---------|-----------| | 4111 2222 3333 4444 | ****-****-****-**** | | 123-45-6789 (SSN) | ***-**-**** | | [email protected] | <email> |

This prevents sensitive data from being sent to LLM context windows where it could be logged or cached.

Design Decisions

• Zero external connections — no telemetry, no cloud sync, no analytics. Everything stays local
• No LLM dependency — this server doesn't call any AI APIs. Your MCP client handles all reasoning
• Lazy session cleanup — sessions expire after 30 minutes of inactivity, checked on each tool call (no background timers)
• Viewport-first element indexing — elements currently visible in the viewport are prioritized and indexed first
• data-mcp-index over CSS selectors — injected attributes are stable across page re-renders, unlike CSS selectors that break with DOM changes

Environment Variables

| Variable | Default | Description | |----------|---------|-------------| | BROWSER_HEADLESS | true | Set to false to show the browser window |

License

MIT