OpenChrome

Harness-Engineered Browser Automation
The MCP server that drives and guides AI agents through a real Chrome.

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What it is

OpenChrome is an MCP server that controls your real, already-logged-in Chrome through the CDP — no middleware, no separate browser, no re-authentication. One Chrome process, many isolated tabs, ~300 MB for 20 parallel lanes.

It is harness-engineered: the server doesn't just expose browser APIs, it wraps them with a hint engine, a circuit breaker, an automatic-recovery runtime, and token-efficient page serialization — so the agent makes fewer mistakes, recovers without "thinking", and burns far fewer tokens.

You: compare "AirPods Pro" prices across Amazon, eBay, Walmart, Best Buy

AI:  [4 parallel lanes, already authenticated everywhere]
     Best Buy $179 · Amazon $189 · Walmart $185 · eBay $172
     live pages · already authenticated · past bot detection

Quick start

Install and point your MCP client at it — one command:

npm install -g openchrome-mcp

openchrome setup                       # Claude Code
openchrome setup --client codex        # Codex CLI (auto-elect topology)
npx openchrome-mcp setup --client opencode   # OpenCode (auto-elect topology)

Restart your MCP client. That's it — Chrome auto-launches on first tool call.

Updating is not configuration migration. npm install -g openchrome-mcp@latest updates the OpenChrome binary, but it does not rewrite existing Claude Code, Codex CLI, OpenCode, or other MCP host registrations. If a release note asks you to move to a new topology (for example isolated profiles, broker mode, or a legacy single-owner or manual broker topology), rerun openchrome setup --client <host> ... or update the host config manually, then restart that host session so the MCP namespace is loaded from the new config.

For manual Codex CLI configuration, run openchrome config --client codex and add the printed [mcp_servers.openchrome] block to ~/.codex/config.toml.

{
  "mcpServers": {
    "openchrome": {
      "command": "openchrome",
      "args": ["serve", "--auto-launch", "--auto-elect", "--minimal"]
    }
  }
}

Prefer no terminal? A one-click desktop app (macOS / Windows / Linux, beta) runs the server with no Node.js setup.

What you can do with it

Ask your agent in plain language — these all map to OpenChrome tools:

• Parallel research — "screenshot AWS billing, GCP, Stripe, Datadog at once" → 4 lanes, one Chrome, already authenticated.
• Authenticated scraping — crawl dashboards and member-only pages using your existing login. No credentials in config.
• Form & flow automation — fill, click, navigate multi-step flows; the agent gets corrective hints when a step drifts.
• Production UI debugging — oc_performance_insights / oc_vitals for LCP/CLS, console_capture, oc_devtools_url to attach live DevTools.
• Site monitoring & diffing — oc_evidence_bundle snapshots + oc_diff for deterministic before/after (DOM, screenshot pHash, network, console).
• Crawling — async crawl_start / crawl_status / crawl_cancel jobs with cursor pagination.
• Verifiable runs — oc_assert checks page state against an Outcome Contract (pass / fail / inconclusive) instead of guessing.

The default surface is 118 tools across navigation, interaction, reading, extraction, parallel workflows, contracts, skills, recovery, and diagnostics. Full catalogue: docs/agent/capability-map.md.

Using it conveniently

Drive it from the shell — no MCP host needed

The CLI can call the MCP surface directly. Great for scripts, CI, and debugging:

oc run navigate --arg url=https://example.com
oc run read_page --arg mode=dom --json
oc navigate https://example.com      # positional sugar for common tools
oc click ref_5

Declarative scenarios with oc playbook

Write a YAML scenario where every step is one tool call with an inline Outcome Contract — deterministic, no LLM judgement:

oc playbook run scenario.yaml --vars url=https://iana.org --out report.md

See docs/cli/playbook.md.

Keep one browser warm — HTTP daemon mode

Run OpenChrome as a long-lived daemon so multiple clients (Claude Code + CI + a dashboard) share one Chrome process, and the server outlives whatever launched it (Docker, systemd, CI):

openchrome serve --http 3100 --auth-token <token> --idle-timeout 30m
curl -s http://127.0.0.1:3100/health

One Chrome process, tabs isolated per session. Without --idle-timeout it stays up until stopped; with it, it self-exits after the idle window. Full guide: docs/getting-started/http-daemon.md.

Diagnose your environment

openchrome doctor      # Node, disk, Chrome binary/port, orphans, perms, locks
openchrome check       # verify CLI + runtime wiring

Token-efficient page reads

read_page mode="dom" serializes the page into a compact text form — ~5–15x fewer tokens than the raw DOM. Each element carries an affordance marker so the agent knows the type at a glance:

# [142]<input type="search" .../> ★      ← # text input
$ [156]<button type="submit"/>Search ★   ← $ button / control
@ [289]<a href="/home"/>Home ★           ← @ link   (% = visual target)

[backendNodeId] identifiers are stable for the node's lifetime — pass 142, node_142, or ref_N to any action tool. oc_observe goes further: it returns a ready-to-act numbered list in one call instead of read_page → query_dom → inspect → interact.

Why agents fail less on OpenChrome

The bottleneck in browser automation is the LLM thinking between steps — every wrong guess costs 10–15s of inference. OpenChrome's harness cuts that loop:

The harness is designed to cut the think-act loop: fewer LLM round-trips, faster wall time, lower cost. Specific speed/cost multipliers are published as headline claims only when backed by live or recorded-real benchmark rows — see docs/benchmarks/benchmark-direction.md.

Other capabilities worth knowing

• Parallel sessions — 1 Chrome, N tabs/lanes; workerId + profileDirectory give per-client isolation. Multiple MCP clients can share one Chrome safely when they connect through a single broker/HTTP owner (--broker / --connect-broker); independent stdio clients should use separate --port / --user-data-dir profiles. If you upgraded OpenChrome after seeing duplicate-controller or -32000 startup failures, also migrate the MCP host config and restart the host; package updates alone do not change existing registrations. See docs/mcp/topologies.md.
• Anti-bot / Turnstile — 3-tier auto-fallback (headless → stealth → real headed Chrome) bypasses CDN/WAF blocks. Turnstile guide.
• Interactive login — headed by default since the launcher runs visible; complete 2FA/CAPTCHA once, reuse the persistent profile after.
• Session persistence — --persist-storage saves cookies + localStorage atomically for headless reuse.
• Shadow DOM — open + closed roots via CDP-pierced reads; __pierce() / __openchrome.querySelectorAllDeep() helpers in javascript_tool.
• Element intelligence — find elements by natural language (AX-first, CSS fallback, Korean role keywords built in: "버튼" → button).
• Core / pilot tiers — core is on by default and preserves the stable surface; --pilot opts into contract runtime, handoff persistence, voting, and the skill curator.

Server & headless deployment

openchrome serve --server-mode     # headless + auto-launch + server defaults

Works in CI/CD and containers with no login — navigation, scraping, screenshots, forms, and parallel workflows all run in clean sessions. A production Dockerfile is included (docker build -t openchrome . && docker run openchrome).

Authentication (per-tenant API keys, JWT/OAuth, shared token): docs/auth.md. Transport stability policy: docs/transport-lifecycle.md.

Host plugins

OpenChrome ships plugin manifests for Claude Code and Codex CLI so both hosts load the MCP server and skill body from the same shared source — no per-host duplication.

Claude Code

Load from the repo for local development:

claude --plugin-dir /path/to/openchrome

Or install from npm after the package is published to a marketplace:

/plugin install openchrome   # once listed in a marketplace

The skill body lives under skills/openchrome/ and the /openchrome:connect slash command is registered from the top-level commands/ directory. Run /reload-plugins after updating to pick up new content.

Manifest: .claude-plugin/plugin.json — registers the openchrome MCP server (openchrome serve --auto-launch). Skills and commands are auto-discovered from skills/ and commands/.

Codex CLI

Load from the repo for local development:

codex --plugin-dir /path/to/openchrome

Or follow the Codex plugin installation instructions once the package is listed in the Codex plugin registry.

Manifest: .codex-plugin/plugin.json — identical MCP server entry point and skill path; the two manifests share the same skills/openchrome/ body.

Shared skill body

Both manifests share skills/openchrome/SKILL.md as the single source of truth for skill content, and the slash command stub at commands/connect.md registers /openchrome:connect. The commands/ directory sits at the plugin root so both hosts auto-discover it.

Documentation

Development

git clone https://github.com/shaun0927/openchrome.git
cd openchrome
npm install && npm run build && npm test

Lint before submitting source changes: npm run lint -- --max-warnings=0 (or npm run lint:changed -- --base origin/develop for changed files only). PRs target the develop branch.

License

MIT