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

Tool	What it does	Needs sign-in
groupon_search_deals	Search or browse a city's deals	no
groupon_get_deal	One deal's detail, including each option's id and price	no
groupon_list_categories	Groupon's category taxonomy	no
groupon_healthcheck	One live request to Groupon, reporting what failed if anything did	no
groupon_view_cart	The items in your Groupon cart	yes
groupon_purchase	Add a deal option to your cart (after you confirm) and return the checkout URL	yes
groupon_clear_cart	Remove every item from your cart (after you confirm)	yes

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).

variable	default
GROUPON_SESSION_COOKIE	unset	Full Cookie header from a signed-in www.groupon.com request, for the cart tools only. Leave unset to have the bridge pick up your session. Treat it like a password.
GROUPON_DISABLE_FETCHPROXY	unset	1 turns the browser-bridge path off; the cart tools then rely on GROUPON_SESSION_COOKIE.
GROUPON_GRAPHQL_URL	https://www.groupon.com/mobilenextapi/graphql	GraphQL endpoint override. The cart tools refuse any override that is not an https://*.groupon.com URL.
GROUPON_CACHE_TTL	60	Response-cache TTL for reads, in seconds (0 = off). Raise it if you hit rate limits.
FETCHPROXY_WS_PORT	37149	Concentrator port the ContextMint Bridge connects to. Every MCP on one machine shares it, so move it for all of them or none.
FETCHPROXY_WS_HOST	127.0.0.1	Bridge bind interface, a literal IP only. Keep on loopback; it exists for hosted deployments in their own network namespace.
FETCHPROXY_IDENTITY_DIR	~/.fetchproxy/identity/	Absolute path for the bridge's long-term identity keypair.

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.

variable	default
MCP_CONFIRM_MODE	ask-user	What a write does on a client that cannot show a confirmation prompt (claude.ai, Claude Desktop). ask-user: two steps — the first call does nothing and returns a preview plus a token, and the model must get your approval in chat before calling again with it. auto: the same two steps, but the model may use the token after reviewing the preview itself. refuse: writes are refused on such clients. A client that can show prompts (Claude Code) always gets the real prompt, unless MCP_CONFIRM_ELICITATION=off. An unrecognised value is treated as refuse.
MCP_CONFIRM_ELICITATION	on	off never shows a confirmation prompt, so every client gets the MCP_CONFIRM_MODE behaviour. Set it for a client that says it can show prompts but never does (the write hangs — opencode 2.0.x). Any other value is treated as on, with a warning on stderr.
MCP_CONFIRM_TTL_SECONDS	600	How long a token stays valid.
MCP_CONFIRM_SECRET	random per process	Signing key; set it only if tokens must survive a server restart.

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