io.github.chrischall/groupon-mcp

groupon-mcp

MCP server for Groupon — search and browse local, goods, and travel deals from Claude via natural language, and add deals to your signed-in Groupon cart once you confirm.

This project was developed and is maintained by AI. Use at your own discretion.

Tools

The deal reads use Groupon's public consumer endpoint with no API key or account. The cart tools act on your signed-in Groupon account through its session cookie (see below). groupon_purchase cannot place an order: Groupon's checkout is native Apple/Google Pay, card or PayPal, so you complete payment yourself at the checkout URL.

Setup

Add the server to your .mcp.json:

{
  "mcpServers": {
    "groupon": {
      "command": "npx",
      "args": ["-y", "groupon-mcp"]
    }
  }
}

Cart sign-in (optional)

Reading deals needs no account. The cart tools (groupon_view_cart, groupon_purchase, groupon_clear_cart) use your signed-in groupon.com session, which the server picks up from your browser through the ContextMint Bridge extension:

1. Install ContextMint Bridge from its releases page. Chrome: download the Chrome zip, unzip it, and load it unpacked at chrome://extensions (Developer mode). Safari isn't available yet (it will ship inside the ContextMint app, which has no public download), so use Chrome for now.

   ContextMint Bridge is the fetchproxy browser extension under its new name, from the same maintainer; fetchproxy's own README (https://github.com/chrischall/fetchproxy#extension) points to it. Its source is public at https://github.com/nullnet-app/contextmint-bridge: build it yourself, or check a release zip against the .sha256 file published beside it (shasum -a 256 -c contextmint-bridge-chrome-<version>.zip.sha256).

2. Sign in at groupon.com in that browser. The first cart call lifts the session cookie; approve the request in the extension when asked.

For local dev without the extension, set GROUPON_SESSION_COOKIE (see .env.example); set GROUPON_DISABLE_FETCHPROXY=1 to turn the browser path off. The cookie authorizes changes to your cart, so treat it like a password. The cart tools only send it to an https://*.groupon.com endpoint, and refuse a GROUPON_GRAPHQL_URL override pointing anywhere else.

Environment

All optional; they mirror the .mcpb manifest's settings (the MCP_CONFIRM_* family is under Confirmations).

Confirmations

The cart writes (groupon_purchase, groupon_clear_cart) ask you to confirm before they change anything. A client that can show a confirmation prompt (Claude Code) shows one, unless the server sets MCP_CONFIRM_ELICITATION=off. Elsewhere, the first call changes nothing and returns a preview plus a confirmToken, and only a repeat call with that token proceeds. The token is tied to exactly what was previewed: if the deal's price, the chosen option or quantity, or the cart's contents change between the two calls, the write is refused and a fresh preview is returned. groupon_purchase's preview also shows how many of that option are already in your cart, since Groupon may set the line to the new quantity rather than add to it. It still only fills the cart; you complete payment yourself at the checkout URL. groupon_clear_cart removes only the cart's line items, and accepts the previewed optionIds back as expectedOptionIds so it refuses if the cart has changed; if a removal fails partway it says which items were and were not removed.

Development

npm install
npm run build   # tsc + esbuild bundle → dist/
npm test        # tsc typecheck + vitest

See CLAUDE.md for architecture, conventions, and gotchas.

License

MIT