Open Claude in Chrome

Claude in Chrome, fully open source. No domain blocklist. Any Chromium browser.

The official Claude in Chrome extension gives Claude Code full browser automation. Open Claude in Chrome is a clean-room reimplementation that removes the restrictions while maintaining 100% feature and performance parity.

Demo: Watch Claude on Tinder, Reddit, and Robinhood | Deep dive: How I reverse-engineered it

What's Different

	Claude in Chrome	Open Claude in Chrome
Domain blocklist	58 blocked domains across 11 categories	No blocklist. Navigate anywhere.
Browser support	Chrome and Edge only	Any Chromium browser (Chrome, Edge, Brave, Arc, Opera, Vivaldi, etc.)
Source code	Closed source	Open source (MIT)
Tools	18 MCP tools	Same 18 MCP tools
Performance	Baseline	Identical

Blocked Domains in the Official Extension

Category	Blocked Sites
Banking	Chase, BofA, Wells Fargo, Citibank
Investing/Brokerage	Schwab, Fidelity, Robinhood, E-Trade, Wealthfront, Betterment
Payments/Transfers	PayPal, Venmo, Cash App, Zelle, Stripe, Square, Wise, Western Union, MoneyGram, Adyen, Checkout.com
BNPL	Klarna, Affirm, Afterpay
Neobanks/Fintech	SoFi, Chime, Mercury, Brex, Ramp
Crypto	Coinbase, Binance, Kraken, MetaMask
Gambling	DraftKings, FanDuel, Bet365, Bovada, PokerStars, BetMGM, Caesars
Dating	Tinder, Bumble, Hinge, Match, OKCupid
Adult	Pornhub, XVideos, XNXX
News/Media	NYT, WSJ, Barron's, MarketWatch, Bloomberg, Reuters, Economist, Wired, Vogue
Social Media	Reddit

Open Claude in Chrome has none of these restrictions.

Architecture

Claude Code <--stdio MCP--> mcp-server.js <--TCP--> native-host.js <--native messaging--> Extension <--> Browser

Three components:

1. Extension — Manifest V3 with CDP-based browser automation (all 18 tools)
2. MCP Server — Node.js process started by Claude Code, exposes tools via MCP
3. Native Messaging Host — Bridge between the MCP server and the extension

Installation

Prerequisites

• Node.js v18+
• Any Chromium browser (Chrome, Edge, Brave, Arc, Opera, Vivaldi, etc.)
• Claude Code v2.0.73+

Step 1: Install dependencies

cd host
npm install
cd ..

Step 2: Load the extension

1. Go to chrome://extensions (or brave://extensions / edge://extensions)
2. Enable Developer mode
3. Click Load unpacked and select the extension/ directory
4. Copy the extension ID shown under the extension name

Step 3: Register native messaging

./install.sh <your-extension-id>

If you use multiple browsers, pass all IDs:

./install.sh <chrome-id> <brave-id> <arc-id>

Step 4: Restart your browser

Close all windows and reopen. The browser reads native messaging host configs on startup.

Step 5: Add to Claude Code

claude mcp add open-claude-in-chrome -- node /absolute/path/to/host/mcp-server.js

Find the absolute path with:

echo "node $(pwd)/host/mcp-server.js"

Verification

Start a new Claude Code session and test:

Navigate to reddit.com and take a screenshot

Reddit loads. No domain restriction.

Available Tools

All 18 tools, identical to Claude in Chrome:

Tool	Description
tabs_context_mcp	Get tab group context
tabs_create_mcp	Create new tab
navigate	Navigate to URL, back, forward
computer	Mouse, keyboard, screenshots (13 actions)
read_page	Accessibility tree with element refs
get_page_text	Extract article/main text
find	Find elements by text/attributes
form_input	Set form values by ref
javascript_tool	Execute JS in page context
read_console_messages	Console output (filtered)
read_network_requests	Network activity
resize_window	Resize browser window
upload_image	Upload screenshot to file input
gif_creator	GIF recording (stub)
shortcuts_list	List shortcuts (stub)
shortcuts_execute	Run shortcut (stub)
switch_browser	Switch browser (stub)
update_plan	Present plan (auto-approved)

Updating After Code Changes

No build step. All files are plain JavaScript. After pulling or editing code:

What changed	What to do
extension/background.js or extension/content.js or extension/manifest.json	Reload the extension: brave://extensions > click the reload icon
host/mcp-server.js	Kill stale servers and reconnect: pkill -f "node.*mcp-server" then /mcp in Claude Code
host/native-host.js	Restart the browser (close all windows, reopen)
install.sh or native host name changed	Re-run ./install.sh <extension-id>, restart browser, re-add MCP

Quick reset (nuclear option)

If things are broken and you're not sure why:

# 1. Kill all MCP servers
pkill -f "node.*mcp-server"

# 2. Re-run install
./install.sh <your-extension-id>

# 3. Restart browser (close all windows, reopen)

# 4. Reload extension in brave://extensions

# 5. Reconnect in Claude Code
# /mcp

Multiple Sessions

Multiple Claude Code sessions can share the same browser extension. The first session becomes the "primary" (owns the TCP port), and subsequent sessions connect as clients through the primary. All sessions can use the browser simultaneously.

If a session disconnects, kill stale servers and reconnect:

pkill -f "node.*mcp-server"
# then /mcp in each Claude Code session

Troubleshooting

Extension not connecting

1. Verify the extension is loaded and enabled
2. Check that ./install.sh was run with the correct extension ID
3. Restart the browser completely (all windows)
4. Verify the native messaging host manifest exists:
   • Chrome (macOS): ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.open_claude_in_chrome.json
   • Brave (macOS): ~/Library/Application Support/BraveSoftware/Brave-Browser/NativeMessagingHosts/com.anthropic.open_claude_in_chrome.json
   • Edge (macOS): ~/Library/Application Support/Microsoft Edge/NativeMessagingHosts/com.anthropic.open_claude_in_chrome.json

MCP server not found

Use an absolute path:

claude mcp add open-claude-in-chrome -- node /absolute/path/to/host/mcp-server.js

"Browser extension is not connected"

The MCP server started but the native host hasn't connected. Try:

1. Open any webpage (wakes the service worker)
2. Check service worker logs: chrome://extensions > "Inspect views: service worker"
3. Verify host/native-host-wrapper.sh exists

Tools fail immediately after reconnect

Stale MCP server processes from previous sessions may be holding the port. Fix:

pkill -f "node.*mcp-server"

Then /mcp in Claude Code to reconnect. The fresh server will bind the port and accept the native host connection.

Port conflict

Default port is 18765. To change:

1. Create ~/.config/open-claude-in-chrome/config.json:

   { "port": 19000 }

2. Restart browser and Claude Code

License

MIT

Built by Sebastian Sosa (Noemica)