io.github.krystiangw/zen

ZEN MCP

An MCP server that lets AI assistants work with the ZEN.com Payment Gateway: hosted payment links, transaction lookup, refunds, payouts, and reporting.

Project page

Unofficial. This project is not affiliated with, endorsed by, or maintained by ZEN.com.

What it does

Read-only tools:

• List terminal payment methods and documented currencies.
• Look up transactions, payment links, and payouts.
• List payment links and request reconciliation reports.
• Verify IPN webhook signatures locally.

Write tools:

• Create hosted payment links and QR codes without handling card data.
• Capture or cancel transactions and issue full or partial refunds.
• Create payouts and customer records.

Disclaimer

This integration was built from public ZEN documentation without access to a live merchant account. Endpoint versions, request fields, response fields, signing details, and webhook behavior must be checked against ZEN's current OpenAPI or Postman collection before production use. Mock mode is included for evaluation without an account.

Install

Add the published package to Claude Code:

claude mcp add zen --env ZEN_API_KEY=your_terminal_api_key -- npx -y @krystiangw/zen-mcp

For Claude Desktop, add this entry to its MCP configuration:

{
  "mcpServers": {
    "zen": {
      "command": "npx",
      "args": ["-y", "@krystiangw/zen-mcp"],
      "env": {
        "ZEN_API_KEY": "your_terminal_api_key",
        "ZEN_PAYWALL_SECRET": "your_paywall_secret",
        "ZEN_IPN_SECRET": "your_ipn_secret",
        "ZEN_ENV": "sandbox"
      }
    }
  }
}

Configuration

Variable	Required	Description
ZEN_API_KEY	Outside mock mode	Terminal API Key sent in Authorization without a Bearer prefix
ZEN_PAYWALL_SECRET	Write operations	Checkout/paywall secret used to sign request bodies
ZEN_IPN_SECRET	Webhook verification	IPN secret used only by verify_webhook_signature
ZEN_ENV	No	sandbox (default) or production
ZEN_BASE_URL	No	API base URL override; takes priority over ZEN_ENV
ZEN_MOCK	No	1 or true enables deterministic offline responses
ZEN_HASH_ALG	No	sha224, sha256 (default), sha384, or sha512

In the ZEN merchant panel, go to my.zen.com → Shop settings → Terminal to find the Terminal API Key. Use sandbox first; the default API host is api.zen-test.com, although sandbox availability and onboarding requirements should be confirmed with ZEN.

No merchant account yet? You can open a ZEN business account. That is a referral link: it credits the author of this project if you sign up through it, and costs you nothing. Every other link in this README is a plain one.

Tools

Name	Type	Description
list_payment_methods	Read	List payment methods for the terminal
get_transaction	Read	Get a transaction by ZEN or merchant ID
list_payment_links	Read	List hosted payment links
get_payment_link	Read	Get one hosted payment link
get_payout	Read	Get a payout by ZEN ID
download_report	Read	Request a report download
list_supported_currencies	Read	List documented supported currencies
verify_webhook_signature	Read	Verify a ZEN IPN signature locally
create_payment_link	Write	Create a hosted checkout link and QR code
refund_transaction	Write, destructive	Issue a full or partial refund
capture_transaction	Write, destructive	Capture an authorized transaction
cancel_transaction	Write, destructive	Cancel a transaction
create_payout	Write, destructive	Send an outbound payout
create_customer	Write	Create a customer record

Security

• Tools are read-only by default; operations that move or reverse money are marked destructive for MCP clients.
• Secrets are read only from environment variables and are never tool arguments.
• Payment acceptance uses ZEN-hosted links, so this server does not collect or transmit card numbers.
• The signing algorithm follows public ZEN documentation, but nested-object and array flattening are not fully specified publicly. Verify it against the live API.
• Verify every IPN webhook signature with ZEN_IPN_SECRET before trusting its contents.
• Use least-privilege terminal credentials and keep human confirmation enabled for write tools.

Demo without an account

Run the server with deterministic canned API responses:

ZEN_MOCK=1 ZEN_IPN_SECRET=demo npx -y @krystiangw/zen-mcp

verify_webhook_signature does real cryptography instead of calling the API, so it needs a secret even in mock mode. Any value works for a demo.

From a development checkout:

npm install
npm run build
ZEN_MOCK=1 ZEN_IPN_SECRET=demo npm run inspect

Development

Requires Node.js 18 or newer.

npm install
npm run typecheck
npm run build
npm test
ZEN_MOCK=1 ZEN_IPN_SECRET=demo npm run inspect

Roadmap

• Raw card charges only after a deliberate PCI/security design; they are excluded from the MVP.
• Recurring and one-click payments after the tokenization flow is verified.
• Consumer ZEN features such as cashback and personal cards if ZEN publishes a supported API.
• Remote Streamable HTTP transport and OAuth after the stdio MVP.

License

MIT