agent-in-chrome

日本語

Two Chrome/Edge extensions that let an AI agent use your browser, plus the native host that connects them to Claude Code, Codex, Devin or any other MCP client. They are open-source reimplementations of Anthropic's "Claude in Chrome" and OpenAI's ChatGPT/Codex browser extension, written from notes on how those extensions behave. No code, prompts or images were copied.

You bring the model. The side panels work with an Anthropic key, an OpenAI key, or any OpenAI-compatible endpoint (DeepSeek, OrcaRouter, OpenRouter, Ollama, LM Studio). If you already use a coding agent, you can skip the side panel and give that agent the browser over MCP.

The two extensions

claude-compat mirrors Claude in Chrome. The agent looks at screenshots and clicks by coordinate, or by element refs from an accessibility tree. It works inside a tab group per conversation. It has the same 23 tools with the same names and input schemas (computer, navigate, read_page, find, form_input, browser_batch, ...), so prompts and tooling written for the original also work here. The side panel adds plan approval, per-site permissions, saved shortcuts with schedules, workflow recording ("Teach") and GIF export.

codex-compat mirrors the Codex browser extension. The extension itself does little. It hands out tabs to agent sessions, passes Chrome DevTools Protocol commands through, and cleans up scratch tabs when a task ends. The agent reads pages as accessibility text with numbered elements and diffs between steps, which keeps token use low and works with text-only models. It can also connect the side panel to a local codex app-server.

Both can be installed at the same time. The Claude-style one suits visual pages. The Codex-style one is cheaper for text-heavy work like research and form filling.

Related MCP server: chrome-mcp

Install

You need Node.js 20 or newer and Chrome, Edge, Brave, Vivaldi or Opera (version 116+).

git clone https://github.com/youseiushida/agent-in-chrome
cd agent-in-chrome
npm install
npm run build
node native-host/dist/aic-install.mjs

aic-install registers the native messaging host for every browser it finds (--browser edge to limit it, --uninstall to undo). Then open chrome://extensions or edge://extensions, turn on developer mode and load these two folders with "Load unpacked":

• extensions/claude-compat/dist

• extensions/codex-compat/dist

Restart the browser once so it picks up the native host.

Using the side panel

Click the extension icon (the Claude-style one also opens with Ctrl+E / ⌘E), pick a provider, paste an API key and describe the task. Keys stay in chrome.storage.local and are only sent to the provider you chose. For DeepSeek, choose "OpenAI-compatible" with base URL https://api.deepseek.com/v1 and model deepseek-flash.

The Claude-style panel starts in "Ask before acting": the agent proposes a plan, you approve it, and it only works on the sites in that plan. "Act without asking" turns prompts off. In the Codex-style panel the same switch is in settings as "Don't ask before using sites".

Using it from Claude Code, Codex or Devin

native-host/dist/aic-mcp.mjs is an MCP server. Use claude for the Claude-style tools or codex for the text-first tools.

# Claude Code
claude mcp add aic-browser -s user -- node /path/to/agent-in-chrome/native-host/dist/aic-mcp.mjs claude

# Devin CLI
devin mcp add -s user aic_browser -- node /path/to/agent-in-chrome/native-host/dist/aic-mcp.mjs codex

For Codex, add this to ~/.codex/config.toml:

[mcp_servers.aic_browser]
command = "node"
args = ["/path/to/agent-in-chrome/native-host/dist/aic-mcp.mjs", "codex"]
tool_timeout_sec = 180

By default the Claude-style server asks before acting on a site. A small "AIC" window pops up in the browser. To let the agent work without prompts, create %APPDATA%\aic\config.json (~/.aic/config.json on macOS/Linux):

{ "permissionMode": "skip_all_permission_checks", "autoApprove": true }

To keep the agent away from certain sites, list them under blockedSites in the same file (used by the codex server) or in the Claude-style extension's options page (used by the claude server). aic-install prints the exact commands for your machine. docs/USAGE.md covers the rest of the options.

Compatibility with the official clients

aic-install --claude-code-compat makes the host listen on the pipe name the official Claude Code browser integration looks for. --codex-compat does the same for the Codex desktop app's browser runtime. In those modes the vendors' own clients can drive these extensions. Don't run them next to the official extensions' hosts; they would fight over the same pipe.

What is not here

Anything that depends on the vendors' accounts or servers is left out. That covers claude.ai sign-in, Anthropic's server-side site safety check (replaced by a local blocklist), pairing with Claude Desktop, and ChatGPT's hosted side chat. The Codex-style tools don't include WebMCP, sign-in handoff or the virtual clipboard yet.

Development

npm test           # unit tests (vitest), ~720 of them
npm run typecheck
npm run e2e        # launches Chromium with both extensions via Playwright

The MCP scenarios in npm run e2e need aic-install --browser chrome,chromium first. They pin themselves to the test browser, so a browser you have open is not touched.

The code is split into packages. protocol holds the wire formats. browser-core holds CDP, screenshots, input, tab groups and permissions. claude-tools has the 23 tools. cdp-actions has the accessibility snapshot and the text-first tool set. agent holds the model providers and the agent loop, and ui the React components. docs/ARCHITECTURE.md describes the protocols. analysis/ has the behavioural notes the implementation was written from (vendor keys and client IDs are redacted).

License

Apache-2.0. Not affiliated with Anthropic or OpenAI. "Claude", "Codex" and "ChatGPT" are their trademarks and appear here only to say what this is compatible with.