Browser Harness ♞

Browser Harness lets Claude Code, Codex or Cursor use your real Chrome browser: open pages, click, type, read and download, logged in as you. Paste one prompt into your coding agent to set it up. It talks to Chrome over the DevTools Protocol (CDP), and the agent writes any missing helper as it works, so the harness gets better with each task. Open source, MIT licensed.

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