render-mcp

Gives an AI agent a real browser. Screenshots, PDFs, and the HTML a page produces after JavaScript has run.

No API key. No signup. No account. Point your client at a URL and it works.

https://render.makermargins.com/mcp

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Why this exists

An agent can fetch a URL. It cannot see one.

Ask an assistant to check whether a page looks right, or to read a site built with React, and it hits a wall: a plain HTTP fetch returns an empty shell and a loading spinner. The content is built by JavaScript that never runs.

The usual answer is a rendering API — but every one of them requires you to sign up, verify an email, and paste an API key. An agent working on its own can't do any of that. It has no inbox and no card. A free tier it cannot register for is worth nothing to it.

This server needs none of it. It runs on Cloudflare's network, launches a real headless browser, and hands back what the page actually looks like.

Install

Claude Code

claude mcp add --transport http render https://render.makermargins.com/mcp

Claude Desktop, Cursor, and other clients — add to your MCP config:

{
  "mcpServers": {
    "render": {
      "type": "http",
      "url": "https://render.makermargins.com/mcp"
    }
  }
}

That's the whole setup. Nothing to install, nothing to configure, no credentials.

Tools

screenshot_url

See a page as a person would. Returns a PNG.

Argument	Type	Notes
url	string	Required. Absolute, including https://
full_page	boolean	Capture the whole scrollable page. Default false
width	number	Viewport width, 320–2560. Default 1280
height	number	Viewport height, 240–2000. Default 800

Good for: confirming a deployment looks right, checking a layout, seeing what a user sees.

rendered_html

The DOM after JavaScript has executed. Returns HTML text.

Argument	Type	Notes
url	string	Required. Absolute, including https://
wait_for	string	CSS selector to wait for, if content loads late
max_chars	number	Truncation limit, 1,000–500,000. Default 100000

Good for: single-page apps, anything where a plain fetch returns a shell.

url_to_pdf

Render a page to PDF as a browser would print it.

Argument	Type	Notes
url	string	Required. Absolute, including https://
landscape	boolean	Default false

Good for: archiving a page, turning a rendered report into a document.

What it won't do

Stated plainly, so an agent doesn't waste calls discovering them:

• No private networks. Loopback, RFC1918 ranges, 169.254.x.x, .internal and .local hostnames are refused. This server runs inside Cloudflare's network and an unvalidated URL would be a server-side request forgery.
• No logins. There's no session, so anything behind authentication renders as its login page.
• 20 second navigation limit. Very slow pages will time out.
• No JavaScript injection. It renders pages; it doesn't run your code on them.

Failures come back as readable text explaining what went wrong, not as protocol errors — so an agent can route around them rather than crashing.

Privacy

Nothing is stored. No logging of URLs, no retention of rendered output, no analytics. Each call launches a browser, does the work, and closes it.

Development

npm install
npm test        # 55 tests, no network or browser needed
npm run dev     # local worker
npm run deploy  # to Cloudflare

The MCP protocol layer in src/protocol.js is pure functions with no Cloudflare or browser dependencies, so the whole request/response surface — including every URL validation rule — is tested under plain Node before anything is deployed. src/index.js is a thin shell that does the browser work.

Status

Early and free. Built to find out whether MCP registry discovery actually works. If it gets used, it'll be maintained; if it doesn't, that's a useful answer too.

Issues and pull requests welcome.

Licence

MIT