> For the complete documentation index, see [llms.txt](https://doc.ecomm.api.tietoevry.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.ecomm.api.tietoevry.com/api-references/unified-merchant-api.md).

# Unified Merchant API

V.1.0.0

Welcome to the Merchant  API documentation—a complete guide to integrating Ecommerce Payment Gateway solution into Merchant platform effortlessly. This documentation provides all the essential details to help Merchants successfully incorporate solution and deliver a secure and user-friendly payment experience for your customers.

The API follows the REST architectural style, where:

* Payments and transactions are treated as resources.
* Standard HTTP methods (e.g., GET, POST) are used to perform operations on resources.
* Each request specifies a media type for resource representation.
* Errors are communicated using standard HTTP response codes.

The payment gateway communicates using the JSON format, with the API format specified in the HTTP header as: `application/json`.

All interactions with the Payments Gateway occur over a secure TLS connection. It is critical that the Merchant API client validates the gateway's certificate to prevent potential Man-in-the-Middle attacks on payment data.

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Payments</strong></td><td>Initiate and process payments, recurring billing</td><td><a href="/api-references/unified-merchant-api/payments.md">Payments</a></td></tr><tr><td><strong>Shops</strong></td><td>Retrieve shop details, including list of available payment methods without initiating a new payment</td><td><a href="/api-references/unified-merchant-api/shops.md">Shops</a></td></tr><tr><td><strong>Tokens</strong></td><td>Token Management </td><td><a href="/api-references/unified-merchant-api/tokens.md">Tokens</a></td></tr><tr><td><strong>Refunds</strong></td><td>Refund payments</td><td><a href="/api-references/unified-merchant-api/refunds.md">Refunds</a></td></tr><tr><td><strong>Callback notifications</strong></td><td>Receive notifications about payment status changes</td><td><a href="/api-references/unified-merchant-api/callback-notifications.md">Callback notifications</a></td></tr></tbody></table>

{% hint style="info" %}
The API reference provided in this documentation is intended for demonstration and informational purposes only. It represents a simulated version of the actual E-Commerce Payment Gateway (EGW) API.

While we strive to ensure accuracy and completeness, the real production API may differ in terms of structure, parameters, authentication flows, or response formats. Final implementation details will be shared with merchants and partners as part of the formal onboarding and integration process.

Tieto reserves the right to modify, extend, or deprecate API endpoints as part of ongoing product development and platform evolution.
{% endhint %}


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