Privacy Policy: Genkan

Last updated: 2026-10-04

Genkan is an open-source browser extension that connects an MCP client (such as Claude Code, Claude Desktop, or Codex) to your local Chromium browser through a native-messaging host that runs on your own computer. This policy explains what the extension accesses and what it does, and does not, do with that data.

Summary

Genkan does not collect, transmit, or sell any personal data. It has no analytics, no telemetry, and no remote servers. Everything the extension does happens on your own machine: sites act only after you approve them, and every high-risk action asks for your confirmation.

What the extension can access

To let an approved AI agent operate the pages you are already signed into, the extension can, only on sites you have explicitly approved (or on all sites, if you enable the explicit allowAllSites opt-in):

• Read the content of the current page (DOM, text, form fields).
• Read cookies for the active site, including httpOnly cookies.
• Read web storage (localStorage / sessionStorage).
• Attach Chrome's debugger to the page (the debugger permission) to read its accessibility tree, read its console, attach a file, or answer a dialog; with the CDP mode setting on, page operations run through it too.
• Execute JavaScript in the page (off by default).
• Attach a local file to a page's file input (off by default; every use shows the exact path for confirmation).

Independent of site approval, it can read the list of open tabs (titles and URLs) and focus a tab. Opening a tab needs an approved site, like any page action; closing one asks for confirmation and, while that confirmation is on, needs an approved site as well.

Unless you turn the tab-grouping setting off, the tabs it opens are gathered into a tab group of their own in each window, so you can tell them apart from yours.

Credential-bearing values (cookies and web storage) are read-only (the extension has no API to write or modify cookies or storage by design) and are masked (JWTs, long hex strings, and long digit runs are redacted) before being returned.

How that data is used and where it goes

• All communication stays on your computer. The extension talks to a local native-messaging host over Chrome's native messaging channel; that host talks to your MCP client over a private, authenticated local socket.
• The extension sends nothing to its authors or to any server of its own. It makes no outbound network requests. What the agent reads is returned to the MCP client you configured, on the same machine, at your request; what that client then does with it (for example, sending page content to the AI service it uses) is governed by that client's own privacy policy, not this one.

Consent and control

• Per-site approval. A site's pages cannot be read or acted on until you approve its origin in a prompt.
• Per-action confirmation. High-risk actions (form submissions, key presses, tab close, file uploads, and, unless you turn that confirmation off, every JavaScript evaluation) confirm in an extension-owned window that web pages cannot see or touch. With the browser's authenticator enrolled (Touch ID, Windows Hello, or a security key), the highest-risk actions ask for a tap on it instead. All are on by default; each is a setting you control.
• A kill switch. You can halt all bridge activity at any time from the extension's options page or the command line; releasing it requires your explicit, present approval.

What the extension stores locally

The extension stores a small amount of configuration in the browser's local extension storage on your device only:

• Your list of approved sites (the allowlist).
• Your extension settings/preferences, including the display language.
• The security policy in force for this extension, as received from the native host (verified against the host's signature once you have paired), and whether the kill switch is engaged.
• If you pair, the fingerprint of the native host's key, used to verify that host (never a private key: the host's key lives in the OS credential store, or in a file in the host's runtime directory when you chose pair --file-store; architecture.md owns where).
• A bounded, local log of recent security decisions (confirmations, revocations), viewable on the options page.

This data never leaves your device and is removed when you uninstall the extension.

Remote code

The extension does not load or execute remotely-hosted code. The JavaScript that may be evaluated in a page is code you (or your MCP client, at your direction) provide locally; it is never fetched from a remote source.

Data sharing and sale

Genkan does not sell or share your data with anyone. The only party that receives anything is the MCP client you yourself configured and pointed at the bridge.

Contact

Questions or concerns: please open an issue at https://github.com/Vivswan/genkan/issues.