# Unified Merchant API

## Introduction

The Merchant API in the EGW ecosystem allows merchants to interact programmatically with the payment gateway, enabling seamless integration of payment functions into their own applications, websites, and back-office systems. It follows best practices from global API standards to ensure security, scalability, and ease of integration.

## Compliance and Standards

The EGW Merchant API is designed to comply with globally recognized standards, ensuring compatibility and regulatory adherence:

* **FAPI 2.0 Compliance**: Meets the security requirements for financial APIs.
* **ISO8583 Standard**: Supports card payment message format.
* **ISO20022 Standard**: Enables structured financial messaging for account-based payments.
* **Berlin Group Framework Compliance**: Supports European open banking standards.
* **Multicurrency Support**: Handles payments in multiple currencies, enabling global transactions.
* **Airline Data Support**: Integration capabilities for airline-specific data processing.

## API Functionalities

* **RESTful Architecture**: Follows the REST architectural style for clear and efficient interaction.
* **Support for CIT and MIT**: Handles both **Customer-Initiated Transactions (CIT)** and **Merchant-Initiated Transactions (MIT)**.
* **Secure Tokenization**: Reduces PCI scope by replacing sensitive data with tokens.
* **Capture, Cancellation, and Refunds**: Simplifies financial workflows with streamlined operations.
* **Callback and Push Notifications**: Instantly notify merchants about transaction status and system events.
* **Recurring Transaction Management**: Automate subscription-based payments and recurring billing cycles.
* **Automated Fund Transfers and Settlements**: Supports seamless payout processing to merchant accounts.

[Go to API References](/api-references/unified-merchant-api.md) 

## Security Best Practices

* **OAuth 2.0 Authentication**: Token-based secure access control.
* **Mutual TLS (mTLS)**: Certificate-based verification for secure connections.
* **Message Signing**: Ensures data integrity during transmission.
* **Audit Logging**: Detailed records of API calls and responses for compliance tracking.

## Monitoring and Error Handling

* **Real-Time Monitoring**: Track API health and performance metrics.
* **Standardized Error Responses**: Follow HTTP status codes with structured JSON error details.
* **API Usage Analytics**: Monitor call volumes, error rates, and response latency.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://doc.ecomm.api.tietoevry.com/integrations/unified-merchant-api.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.