@stackcurious/polar-mcp

An MCP server that gives AI agents control of Polar.sh — products, checkouts, subscriptions, customers, and license keys. Drop into Claude, Cursor, Windsurf, or any MCP client and let your agent run your billing.

Polar is a developer-first billing platform. This server makes it agent-first.

Why

Polar's web dashboard is excellent for humans. This server is for the other half of your team — your agents — that should be able to ask:

• "Create a checkout link for the Pro tier"
• "How many active subscribers do I have on the Founder plan?"
• "Show me last week's orders sorted by revenue"
• "Validate this license key for me"

…and have it just work, without you opening the dashboard.

Tools

| Tool | Description | |------|-------------| | polar_list_products | List products, filtered by org / archived / recurring | | polar_get_product | Fetch one product including prices and benefits | | polar_list_subscriptions | List subscriptions, filtered by product / customer / active | | polar_get_subscription | Fetch one subscription | | polar_list_orders | List orders (one-time + sub invoices) | | polar_get_order | Fetch one order | | polar_list_customers | List customers, filtered by email or query | | polar_get_customer | Fetch one customer | | polar_get_customer_state | Snapshot of customer's active subs, granted benefits, recent orders | | polar_create_checkout | Create a checkout session and return the URL | | polar_get_checkout | Fetch an existing checkout session | | polar_validate_license_key | Validate a license key against your org | | polar_list_license_keys | List license keys issued by your org | | polar_list_webhook_endpoints | List registered webhook endpoints |

14 tools covering ~80% of operational queries. Refunds, benefit grants, and customer-portal sessions are intentionally excluded from v0.1 — they're either high-blast-radius writes or need a different auth model. File an issue if you need them.

Setup

1. Install

npm install -g @stackcurious/polar-mcp

2. Get an Organization Access Token

Polar dashboard → Settings → Developer → Access Tokens → create one with the scopes you need (typically read on everything + write on checkouts:create).

The token starts with polar_oat_…. Keep it server-side.

3. Configure your MCP client

Claude Code:

claude mcp add polar -- env POLAR_ACCESS_TOKEN=polar_oat_your_token npx @stackcurious/polar-mcp

Claude Desktop / Cursor / Windsurf — add to your MCP config:

{
  "mcpServers": {
    "polar": {
      "command": "npx",
      "args": ["@stackcurious/polar-mcp"],
      "env": {
        "POLAR_ACCESS_TOKEN": "polar_oat_your_token",
        "POLAR_SERVER": "production"
      }
    }
  }
}

4. Use it

Restart your MCP client and ask:

• "List my Polar products."
• "Create a checkout for the Pro plan and email me the link."
• "How many active subscribers do I have, and what's my MRR?"
• "Validate license key XYZ-123-ABC."

Sandbox vs Production

Set POLAR_SERVER=sandbox to point at https://sandbox-api.polar.sh/v1 for testing without touching real customers. Defaults to production.

POLAR_SERVER=sandbox POLAR_ACCESS_TOKEN=polar_oat_sandbox npx @stackcurious/polar-mcp

Rate Limits

Polar allows 500 requests/minute on production, 100/min on sandbox. This server doesn't queue or throttle — if you hit a 429, the SDK throws and the MCP returns the error to your agent. In practice, agent workloads stay well under the limit.

Switching from RevenueCat?

We wrote up the migration: Switch from RevenueCat to Polar in 30 minutes. It pairs with @stackcurious/revenuecat-charts-mcp if you want analytics on the RC side.

Webhooks

This MCP server doesn't receive webhooks (out of MCP scope — the agent is the consumer, not the server). For inbound webhook handling in your own app, use Polar's official standardwebhooks library:

import { Webhook } from "standardwebhooks";

const wh = new Webhook(process.env.POLAR_WEBHOOK_SECRET!);
const payload = wh.verify(rawBody, headers);

Requirements

• Node.js 18+
• A Polar Organization Access Token (polar_oat_…)

Built by

Q — an autonomous AI agent platform. This server is one of a small family of @stackcurious/*-mcp packages giving agents real grip on developer tools. See also: @stackcurious/revenuecat-charts-mcp.

License

MIT.