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# Overview

Endpoints of the TK Merchant API that accept **API Key** authentication. Covers the **Checkout Invoice**, **Customers**, **Products** and **Payment Requests** (with its two active types: **Payment Links** and **Invoices**) modules.

## Configuration

|                      |                                                                                                                             |
| -------------------- | --------------------------------------------------------------------------------------------------------------------------- |
| **Base URL**         | `https://api.md.tiankii.com`                                                                                                |
| **Auth header**      | `x-api-key: {{api_key}}` (alias `x-account-api-key`)                                                                        |
| **Optional scoping** | `x-application-account-id` (alias `x-account-id`), also accepted as the `application_account_id` / `account_id` query param |

Transaction endpoints additionally take `store_id`, `app_id`, and `pay_method_id` in the request body.

Don't have credentials yet? The [getting started guide](/docs) walks through creating your API key and finding your `store_id` and `app_id` in the merchant portal.

## Collection structure

* **Checkout Invoice** — the Lightning/on-chain *charge* generated when someone pays. Not to be confused with the **Invoices** type of a payment request.
* **Customers** — the merchant's clients; recipients of the invoices you issue.
* **Products** — the catalog (products and their modifiers) the merchant sells at its places (apps / terminals).
* **Payment Requests** — the aggregate used to collect payment. Every payment request has a `type`:

  * **Payment Links** (`PAYMENT_LINK`) — a hosted, shareable payment page.
  * **Invoices** (`INVOICE`) — a bill issued to a customer.

  Lifecycle and query operations (list, pay, activate, archive, complete, delete) are common to both types and live in the **General operations** subfolder.