README.md

OpenCode Browser

Browser automation for OpenCode via Chrome extension + Native Messaging.

Inspired by Claude in Chrome - Anthropic's browser extension that lets Claude Code test code directly in the browser and see client-side errors via console logs. This project brings similar capabilities to OpenCode.

"Claude in Chrome runs in a side panel that stays open as you browse, working with your existing logins and bookmarks." — @claudeai, Dec 18, 2024

Why?

Chrome 136+ blocks --remote-debugging-port on your default profile for security reasons. This means DevTools-based automation (like Playwright or chrome-devtools-mcp) triggers a security prompt every time.

OpenCode Browser bypasses this entirely using Chrome's Native Messaging API - the same approach Claude uses. Your automation works with your existing browser session, logins, and bookmarks. No prompts. No separate profiles.

Installation

npx opencode-browser install

The installer will:

1. Copy the extension to ~/.opencode-browser/extension/
2. Open Chrome for you to load the extension
3. Register the native messaging host
4. Optionally update your opencode.json

Manual Setup

If you prefer manual installation:

1. Load the extension

   • Go to chrome://extensions
   • Enable "Developer mode"
   • Click "Load unpacked" and select ~/.opencode-browser/extension/
   • Copy the extension ID

2. Run the installer to register the native host:

   npx opencode-browser install

3. Add to opencode.json:

   {
     "mcp": {
       "browser": {
         "type": "local",
         "command": ["npx", "opencode-browser", "start"],
         "enabled": true
       }
     }
   }

Available Tools

Tool	Description
browser_navigate	Navigate to a URL
browser_click	Click an element by CSS selector
browser_type	Type text into an input field
browser_screenshot	Capture the visible page
browser_snapshot	Get accessibility tree with selectors
browser_get_tabs	List all open tabs
browser_scroll	Scroll page or element into view
browser_wait	Wait for a duration
browser_execute	Run JavaScript in page context

Architecture

OpenCode ──MCP──> server.js ──Unix Socket──> host.js ──Native Messaging──> Chrome Extension
                                                                                  │
                                                                                  ▼
                                                                            chrome.tabs
                                                                            chrome.scripting

• server.js - MCP server that OpenCode connects to
• host.js - Native messaging host launched by Chrome
• extension/ - Chrome extension with browser automation tools

No DevTools Protocol = No security prompts.

Uninstall

npx opencode-browser uninstall

Then remove the extension from Chrome and delete ~/.opencode-browser/ if desired.

Logs

Logs are written to ~/.opencode-browser/logs/browser-mcp-host.log

Platform Support

• macOS ✓
• Linux ✓
• Windows (not yet supported)

License

MIT

Credits

Inspired by Claude in Chrome by Anthropic.