About browser-harness

Browser Harness is a self-healing software that connects Large Language Models directly to a real browser via a thin, editable Chromium DevTools Protocol harness. Designed for complex browser automation tasks requiring complete freedom, it operates with a single websocket to Chrome, eliminating intermediate layers. The system is unique because the agent dynamically writes missing helper code during execution, allowing the harness to improve itself with every run. Setup involves enabling remote debugging in Chrome and pasting a setup prompt into an LLM interface. It supports connection to personal browsers as well as a free cloud tier offering concurrent browsers, proxies, and captcha solving. The lightweight architecture consists of approximately 1,000 lines across four core files, including protected core packages and an agent workspace for editable helpers and domain-specific skills. Users can enable community-contributed per-site playbooks to guide the agent on specific websites. The software learns from s

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README.md

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Browser Harness ♞

Connect an LLM directly to your real browser with a thin, editable CDP harness. For browser tasks where you need complete freedom.

One websocket to Chrome, nothing between. The agent writes what's missing during execution. The harness improves itself every run.

  ● 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.

Setup prompt

Paste into Claude Code or Codex:

Set up https://github.com/browser-use/browser-harness for me.

Read `install.md` and follow the steps to install browser-harness and connect it to my browser.

The agent will open chrome://inspect/#remote-debugging. Tick the checkbox so the agent can connect to your browser:

Click Allow when the per-attach popup appears (Chrome 144+):

See agent-workspace/domain-skills/ for example tasks.

Free Browser Use Cloud browsers

Stealth, sub-agents, or headless deployment.
Browser Use Cloud free tier: 3 concurrent browsers, proxies, captcha solving, and more. No card required.

Grab a key at cloud.browser-use.com/new-api-key
Or let the agent sign up itself via docs.browser-use.com/llms.txt (setup flow + challenge context included).

Architecture (~1k lines across 4 core files)

install.md — first-time install and browser bootstrap
SKILL.md — day-to-day usage
src/browser_harness/ — protected core package
agent-workspace/agent_helpers.py — helper code the agent edits
agent-workspace/domain-skills/ — reusable site-specific skills the agent edits

Contributing

PRs and improvements welcome. The best way to help: contribute a new domain skill under agent-workspace/domain-skills/ for a site or task you use often (LinkedIn outreach, ordering on Amazon, filing expenses, etc.). Each skill teaches the agent the selectors, flows, and edge cases it would otherwise have to rediscover.

Skills are written by the harness, not by you. Just run your task with the agent — when it figures something non-obvious out, it files the skill itself (see SKILL.md). Please don't hand-author skill files; agent-generated ones reflect what actually works in the browser.
Open a PR with the generated agent-workspace/domain-skills/<site>/ folder — small and focused is great.
Bug fixes, docs tweaks, and helper improvements are equally welcome.
Browse existing skills (github/, linkedin/, amazon/, ...) to see the shape.

If you're not sure where to start, open an issue and we'll point you somewhere useful.

Domain skills

Set BH_DOMAIN_SKILLS=1 to enable agent-workspace/domain-skills/ — community-contributed per-site playbooks goto_url surfaces by domain. Contribute via PR.

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

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