Claudezilla MCP
An MCP server and Firefox extension that let Claude Code open pages, click, type and take screenshots without Chrome
- 46 ★ on the repository
- Last commit
- MIT
Extended access
Why this level
- The agent clicks and types on sites, including tabs where you are already signed in
- `firefox_evaluate` runs JavaScript on the page, so it stays behind a separate switch
Install
- Works in
Manual install
git clone https://github.com/boot-industries/claudezilla.git
cd claudezilla
./install/install-macos.shThe macOS command; on Linux run `./install/install-linux.sh`. The script installs the native host and dependencies and registers the server with Claude Code.
Access and checks
How we reviewExtended accessThe tool runs code or makes network calls and only reads external data.
- The agent clicks and types on sites, including tabs where you are already signed in
- `firefox_evaluate` runs JavaScript on the page, so it stays behind a separate switch
This is third-party code. Review the repository files before installing.
What it does
Claudezilla connects Claude Code to Firefox. The browser extension receives commands through a local socket and a Node.js native host, and the MCP server gives the agent tools such as `firefox_navigate`, `firefox_click`, `firefox_type` and `firefox_screenshot`. It works in regular and private windows. The agent reads page text (up to 50,000 characters), builds an accessibility tree, waits for an element, text or URL, scrolls, and dismisses cookie and GDPR banners. `firefox_attach_tab` takes a tab you already have open and drives it in place. A shared pool of 12 tabs serves several Claude Code sessions at once: each has its own identifier and leaves other sessions' tabs alone. There are also focus loops (`firefox_start_loop` repeats a task up to a set number of iterations), a domain allowlist through `firefox_set_config` and a private mode switch. Tool categories load on demand through `firefox_activate`, which saves about 6,000 tokens of context.
Who it is for. Users of Linux, Tails and Qubes, and teams whose policy rules out Chrome but whose agent still needs a browser.
Good fit when
- Chrome cannot be installed on the workstation, yet the agent has to check a page and take a screenshot
- A dynamic site loads slowly, so the agent waits for specific text and then collects links, headings and buttons
- Several Claude Code sessions use the browser at once and must not grab each other's tabs
- You opened a page by hand and want to hand that tab to the agent so it can continue the scenario
Not a fit when
- Chrome is available: Anthropic's official browser tool works with it, so a second stack adds nothing
- The agent runs in Cursor or Codex: the installer registers the server with Claude Code only
- The agent needs arbitrary JavaScript on a page with no manual steps: `firefox_evaluate` is off by default and turns on with a switch in the extension popup
Example request
Open https://example.com, take a screenshot and collect all links from the page.MCP
- Transport
- stdio
- Authentication
- not required
Environment variables
CLAUDEZILLA_IPC_DIR- Directory for the IPC socket, auth token and debug log, POSIX only. Needed to run two browsers side by side.
CLAUDEZILLA_AUTOSTART_CMD- Command that starts the browser when the host is unreachable. Never run through a shell.
Limitations
Setup takes two steps: the extension from Firefox Add-ons and a native host installed by a script from the repository (separate for macOS and Linux). Firefox 91 and Node.js 18 or newer are required.
The installer adds permissions for the Claudezilla tools to `~/.claude/settings.json`. `firefox_evaluate` is not in that list.
The repository names Claude Code as the only client. Use in other agents is not described by the author.
The extension asks for a donation through Stripe.
How to disable. Remove the server with `claude mcp remove claudezilla`, uninstall the Claudezilla extension from Firefox and delete the added permissions from `~/.claude/settings.json`.
FAQ
How is Claudezilla different from Anthropic's browser tool?
Claudezilla drives Firefox, while Anthropic's official browser tool requires Chrome. By the author's description the actions match: clicks, typing, screenshots, JavaScript, and DevTools console and network.
Does page data leave the computer?
Claudezilla keeps commands on the computer: they go through a local Unix socket, or a named pipe on Windows. The author states there is no telemetry. Page text does reach the model context, as with any browser tool.
How do I turn on JavaScript evaluation?
Open the extension popup, go to Settings and enable Allow JavaScript evaluation. Then add `mcp__claudezilla__firefox_evaluate` to `permissions.allow` in `~/.claude/settings.json`.
Which versions does it need?
Firefox 91 or newer and Node.js 18 or newer. Of the agents, the project names Claude Code only.
Can two browsers run side by side?
Yes. For each pair of a browser and a Claude Code session, set its own shared `CLAUDEZILLA_IPC_DIR` and restart the MCP server. A visible profile and a background profile can run side by side this way.
Discussion
No questions or reviews yet.
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Comparison with similar tools
Cards that share the main search query, and how they differ.
| Tool | Official | Authentication | Repository stars | Main difference |
|---|---|---|---|---|
| Claudezilla (this card) | yes | not required | 46 | |
| Firefox DevTools MCP | yes | not required | 567 | Mozilla's server on WebDriver BiDi with no browser extension |
| Playwright MCP | yes | not required | 39,570 | drives a Playwright browser by accessibility tree, Firefox is optional |
README in short
The repository covers macOS and Linux setup, environment variables for the socket and browser autostart, the full tool list and the security model: a command whitelist, URL validation, blocked `javascript:` and `data:` schemes and pinned dependencies. The project is free and open source under MIT.