Browser Harness ♞

Connect an LLM directly to your real browser through one editable CDP websocket. The agent writes missing helpers as it works, so the harness improves with every task.

Try browser-harness in Browser Use Cloud or paste the setup prompt into your coding agent.

  ● agent: wants to upload a file
  │
  ● agent-workspace/agent_helpers.py → helper missing
  │
  ● agent writes it                         agent_helpers.py
  │                                                       + custom helper
  ✓ file uploaded

You will never use the browser again.

See it work

Task: "Open my X profile, find my latest 20 video posts, and download them."

Setup prompt

Paste into Claude Code or Codex:

Install or upgrade browser-harness to the latest stable version with uv using Python 3.12, register the skill from `browser-harness skill`, and connect it to my browser. Ask whether I want local browser recordings enabled; default to no and preserve my existing preference on upgrades. Follow https://github.com/browser-use/browser-harness/blob/main/install.md if setup or connection fails.

The agent will open chrome://inspect/#remote-debugging. On first setup, tick the checkbox so the agent can connect to your browser:

How it works

• install.md connects the agent to your browser.
• SKILL.md teaches it the browser workflow.
• src/browser_harness/ stays protected while the agent writes reusable helpers in its local workspace.

Scale with Browser Use Cloud

Use your local browser for logged-in, personal work. When you want many browsers in parallel—with live previews, proxies, stealth, CAPTCHA solving, and more—scale with Browser Use Cloud.

MCP server

browser-harness-mcp exposes the browser control helpers as MCP tools over stdio, so any MCP client (Claude Code, Devin, Cursor, etc.) can drive the browser without writing a second CDP layer. See docs/MCP.md for setup and client configuration.

Contributing

Bug fixes, documentation improvements, and agent-generated domain skills are welcome. See CONTRIBUTING.md.

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The Bitter Lesson of Agent Harnesses · Web Agents That Actually Learn