Content
# Controlium
**Let Claude drive your real Chrome.** Controlium is a Chrome extension + local MCP
bridge that gives Claude — in **Claude Code** *and* **Claude Desktop** — control of your
browser over the Chrome DevTools Protocol: navigate, click, type, scroll, screenshot,
read pages, run JS. It does what the official "Claude in Chrome" extension does, with two
differences:
- 🔝 **It brings the working tab to the front.** Every action first makes the target tab
the active, visible tab and focuses its window. Claude's tab is never hidden in the
background. (The official extension deliberately drives background tabs — see
[RESEARCH.md](RESEARCH.md).)
- ✨ **It shows a synthetic cursor.** A glowing pointer animates to each click with a
ripple, so you can watch Claude work — and it shows up in screenshots too.
It runs in **your normal Chrome profile** (your logins, your tabs), not a throwaway
instance.
```
Claude Code / Claude Desktop / Claude WORK … (any number of MCP clients)
│ stdio
▼
mcp-server/server.js (thin client; auto-starts the daemon)
│ WebSocket → 127.0.0.1:8765
▼
mcp-server/bridge.js ── ONE shared daemon; owns the port + the extension link
│ WebSocket
▼
extension service worker
│ chrome.debugger (CDP) + chrome.tabs / chrome.windows
▼
your Chrome tab ──▶ brought to the FRONT, with a visible cursor
```
Every Claude app connects to a single shared bridge daemon on port 8765, so any
number of them coexist without fighting over the port. The daemon starts
automatically the first time any Claude launches the MCP server.
## Quick start
```bash
git clone https://github.com/am-will/controlium.git
cd controlium
./install.sh
```
The installer:
1. installs the MCP server's dependencies,
2. registers the MCP server with **Claude Code** (`claude mcp add controlium`),
3. builds the **Claude Desktop** bundle (`build/controlium.mcpb`),
4. copies the extension's path to your clipboard and prints the one manual step.
Then **load the extension** (the one thing Chrome won't let a script do):
1. open `chrome://extensions`
2. turn on **Developer mode** (top-right)
3. click **Load unpacked** and choose the **`extension/`** folder (already on your clipboard)
It appears as **Controlium** — the toolbar dot turns green once it's connected. Now ask
Claude to control your browser.
Installer options: `./install.sh --code-only`, `--desktop-only`, `--no-desktop`,
`--open-desktop` (macOS: also pops the Claude Desktop install dialog).
## Manual setup
<details>
<summary><b>Chrome extension</b></summary>
Chrome blocks loading unpacked extensions from the command line in branded builds, so load
it once through the UI: `chrome://extensions` → **Developer mode** → **Load unpacked** →
select the `extension/` folder. It persists across restarts. The popup has a status dot
and toggles for **bring-to-front** and the **synthetic cursor**.
</details>
<details>
<summary><b>Claude Code</b></summary>
```bash
claude mcp add controlium --scope user -- node "$(pwd)/mcp-server/server.js"
```
Claude Code launches the server (bridge on port **8765**); the extension auto-connects.
Verify with `claude mcp list`.
</details>
<details>
<summary><b>Claude Desktop</b></summary>
Recent Claude Desktop builds manage `claude_desktop_config.json` themselves and overwrite
hand-added `mcpServers`, so install it as a **Desktop Extension** (`.mcpb`) instead:
```bash
./scripts/build-mcpb.sh # produces build/controlium.mcpb
open -a Claude build/controlium.mcpb # opens the install dialog (macOS)
```
Or: Claude Desktop → **Settings → Extensions → Advanced settings → Install Extension…**
→ pick `build/controlium.mcpb`. (Use the **Extensions** section, *not* **Connectors** —
Connectors is only for remote URL-based servers.)
Multiple Claude Desktop profiles (e.g. a separate "WORK" install) each install the same
bundle. Everything — Claude Code and every Desktop profile — shares the one bridge daemon
on **8765**, so there are no per-app ports to manage. Drive from one at a time.
</details>
## Tools Claude can call
| Tool | Description |
|------|-------------|
| `list_tabs` | List open tabs (id, title, url, active, window). |
| `focus_tab` | **Bring a tab to the front** (active + window focused). |
| `new_tab` / `close_tab` | Open / close a tab. |
| `navigate` | Go to a URL (or `back` / `forward`); waits for load. |
| `screenshot` | PNG of the viewport (CSS-pixel space; matches click coords). |
| `read_page` | Accessibility-style outline with `[ref_N]` handles. |
| `get_page_text` | Visible page text. |
| `find` | Find elements by label; returns refs + coordinates. |
| `click` | Click a coordinate or a ref (with the visible cursor). |
| `move_mouse` / `hover` | Move the synthetic cursor / trigger hover. |
| `type_text` | Type into the page (optionally click-to-focus, then submit). |
| `press_key` | Keys and combos (`Enter`, `Tab`, `Ctrl+A`, `Meta+L`, …). |
| `scroll` | Scroll by direction/amount or dx/dy. |
| `eval_js` | Run JS in the page and return the result. |
| `read_console` / `read_network` | Buffered console / network activity. |
| `resize_window` | Resize the tab's Chrome window. |
Every tab-targeting tool honors the **bring-to-front** setting; pass `focus: false` on a
call to skip it just for that call.
## Configuration
- **Bridge port** — everything shares one daemon on `127.0.0.1:8765`. The extension's
**Bridge ports** field defaults to `8765, 8766, 8767` (extra entries are just harmlessly
retried); `8765` is all you need. Override with the `CONTROLIUM_PORT` env var if 8765 is
taken.
- **Bring to front** and **Synthetic cursor** — toggles in the popup/options, both on by
default.
## Development
| Path | What it is |
|------|-----------|
| `extension/` | The MV3 Chrome extension (service worker, cursor overlay, popup, options). |
| `mcp-server/` | Node MCP server + localhost WebSocket bridge. |
| `desktop-extension/` + `scripts/build-mcpb.sh` | Source + builder for the Claude Desktop `.mcpb`. |
| `tests/` | `integration.mjs` (no browser) and `live-e2e.mjs` (real Chromium). |
| `RESEARCH.md` | How the official extension works (reverse-engineered). |
```bash
npm install # dev deps (ws) for the tests
npm test # protocol/bridge test — no browser needed
# Full browser test needs a Chromium that honors --load-extension:
npx @puppeteer/browsers install chrome@stable
CHROME_BIN="/path/to/Chrome for Testing" npm run test:live
```
## Notes & limits
- Uses `chrome.debugger`, so Chrome shows a *"…started debugging this browser"* banner
while active — the price of CDP access, same as the official extension.
- Only one CDP client can attach to a given tab; if the official Claude extension is
attached to the same tab, use a different tab (or disable it there).
- Drive from **one host at a time**. Both bridges can be connected, but issuing commands
from Claude Code and Claude Desktop simultaneously will fight over the same tabs.
- After a bridge (re)starts, a sleeping service worker can take up to ~30s to reconnect;
any browser activity wakes it sooner.
## License
[MIT](LICENSE)
