open-claude-in-chrome

The official Claude in Chrome extension gives Claude Code full browser automation — as long as you stay within Anthropic's allowlist of "safe" sites. Open Claude in Chrome is a clean-room reimplementation that strips the restrictions while keeping all 18 MCP tools and matching the official extension's performance.

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)