auth-fetch-mcp

MCP server that lets AI assistants fetch content from authenticated web pages.

When your AI tries to read a URL that requires login, this tool opens a real browser for you to sign in — then captures the page content as cleaned HTML. Sessions are saved locally, so you only log in once per service.

Demo

auth-fetch-mcp demo

Quick Start

Claude Code

Terminal

claude mcp add --scope user auth-fetch -- npx auth-fetch-mcp@latest

.mcp.json (Cursor, Windsurf, etc.)

config.json

{
  "mcpServers": {
    "auth-fetch": {
      "command": "npx",
      "args": ["auth-fetch-mcp@latest"]
    }
  }
}

Chromium is auto-installed on first run if not already present.

How It Works

Ask your AI to read any authenticated page — just paste the URL.
A browser window opens automatically and navigates to the page.
Log in as you normally would (supports SSO, 2FA, CAPTCHA — anything).
Click the "📸 Capture" button in the bottom-right corner when ready.
The page content is captured as cleaned HTML (noise elements stripped, media tags preserved), the browser closes, and your AI receives the content.

Tools

`auth_fetch`

The primary tool. Fetches page content using a real browser, opening a window for login if needed. Returns cleaned HTML with noise elements (nav, footer, scripts, etc.) stripped and media tags (<img>, <video>, <iframe>) preserved.

Parameter	Type	Required	Description
`url`	string	yes	The URL to fetch content from (only `http`/`https`; see URL restrictions)
`wait_for`	string	no	CSS selector to wait for before capturing (useful for SPAs)

`download_media`

Downloads files from URLs using saved browser sessions. Use this to lazily download images, videos, or other files found in auth_fetch results. The browser's saved cookies handle authentication automatically — no need to log in again.

Parameter	Type	Required	Description
`urls`	string[]	yes	One or more URLs to download (only `http`/`https`; see URL restrictions)
`output_dir`	string	no	Subdirectory under `~/.auth-fetch-mcp/downloads/` to save files into. Absolute paths or `..` segments that escape this root are rejected. Defaults to `~/.auth-fetch-mcp/downloads/<timestamp>/`

Example flow:

Code

1. auth_fetch("https://notion.so/my-page")
   → Returns HTML with <img src="https://s3.notion.so/signed-url..."/> tags

2. AI reads the HTML, identifies an image it needs

3. download_media(["https://s3.notion.so/signed-url..."])
   → Downloads the image using saved session cookies
   → Returns { localPath: "~/.auth-fetch-mcp/downloads/.../file-1.png" }

`list_pages`

Lists all open tabs in the browser with their URLs and titles.

`close_browser`

Closes the browser window. Login sessions are saved and will be reused next time.

URL restrictions

To prevent SSRF (server-side request forgery) attacks driven by prompt injection, both auth_fetch and download_media validate every URL before dispatching it:

Only http and https schemes are allowed. file:, data:, javascript:, etc. are rejected.
The hostname is resolved via DNS and the resulting IP is checked. Requests are rejected when the address falls in private, loopback, link-local, CGNAT, or multicast ranges:
- IPv4: 0.0.0.0/8, 10.0.0.0/8, 100.64.0.0/10, 127.0.0.0/8, 169.254.0.0/16, 172.16.0.0/12, 192.0.0.0/24, 192.168.0.0/16, 198.18.0.0/15, 224.0.0.0/4, 240.0.0.0/4
- IPv6: ::, ::1, fc00::/7, fe80::/10, ff00::/8, IPv4-mapped equivalents
download_media additionally constrains output_dir to stay inside ~/.auth-fetch-mcp/downloads/. Absolute paths and .. segments that escape this root are rejected.

Allowing private hosts

If you need to access a host on your local machine or LAN (e.g., a dev server, NAS, or Tailscale node), opt in with environment variables:

Variable	Effect
`AUTH_FETCH_ALLOW_PRIVATE`	Set to `1`, `true`, or `yes` to disable all private/loopback/link-local checks. Most permissive — use only in trusted environments.
`AUTH_FETCH_ALLOW_HOSTS`	Comma-separated allowlist of hostnames or IPs. Matches against the URL's hostname and every resolved IP.

.mcp.json example:

config.json

{
  "mcpServers": {
    "auth-fetch": {
      "command": "npx",
      "args": ["auth-fetch-mcp@latest"],
      "env": {
        "AUTH_FETCH_ALLOW_HOSTS": "localhost,127.0.0.1,192.168.1.10"
      }
    }
  }
}

Heads up: enabling these variables re-opens those hosts to any prompt the MCP client (LLM) processes. Prefer the narrowest possible allowlist over AUTH_FETCH_ALLOW_PRIVATE=1, and only enable them in environments you trust.

Data Storage

All data is stored locally under ~/.auth-fetch-mcp/. Nothing is sent to external servers.

What	Where	When	Persistent?
Browser sessions (cookies, local storage)	`~/.auth-fetch-mcp/browser-data/`	After first login	Yes — reused across restarts
Downloaded media files	`~/.auth-fetch-mcp/downloads/<timestamp>/`	Only when `download_media` is called	Yes — stays until you delete it
Captured page content (HTML)	Not saved to disk	Passed directly to AI via stdio	No — exists only in the AI's context

To clear all data:

bash

# Clear login sessions only
rm -rf ~/.auth-fetch-mcp/browser-data/

# Clear downloaded files only
rm -rf ~/.auth-fetch-mcp/downloads/

# Clear everything
rm -rf ~/.auth-fetch-mcp/

Supported AI Tools

Claude Code
Cursor
Windsurf
Any MCP-compatible client using stdio transport

Limitations

Requires a local environment (does not work in web-based chat interfaces)
First access to each service requires manual login
Very long pages are truncated to fit LLM context windows (100K chars)
Some sites with aggressive bot detection may not work (try the wait_for option)
Private, loopback, and link-local hosts are blocked by default — opt in via AUTH_FETCH_ALLOW_PRIVATE / AUTH_FETCH_ALLOW_HOSTS (see URL restrictions)

Privacy

All data stays on your machine — nothing is sent to external servers
Captured HTML is never written to disk — it only passes through the stdio pipe to the AI tool
Browser sessions are stored locally as a standard Chromium profile
Downloaded files go to a local directory you control

Contributing

Contributions are welcome! Please open an issue or submit a pull request.

bash

git clone https://github.com/ymw0407/auth-fetch-mcp.git
cd auth-fetch-mcp
npm install
npm run build

License

MIT