> ## Documentation Index
> Fetch the complete documentation index at: https://docs-payment-merchant.keysecure.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Access Guide

## Integration Mode Overview

### Credit Extension Mode (CREDIT\_EXTENSION)

Cardholder's actual assets, including deposits and withdrawals, are managed in a closed loop on the merchant's side. All cardholder funds are managed by the merchant themselves.

Merchants complete credit extension through fund transfers and need to recharge reserve funds. When cardholders consume, funds are deducted from the reserve.

**Applicable Scenarios:**

* Merchant manages cardholder funds independently
* Requires complete account system and transfer functionality
* Relatively low real-time requirements

### Authorization Mode (AUTHORIZATION)

Cardholder's actual assets, including deposits and withdrawals, are managed in a closed loop on the merchant's side. All cardholder funds are managed by the merchant themselves.

When cardholders make purchases, KeySecure sends authorization confirmation to the merchant, which must be completed **within 800 milliseconds**, otherwise the transaction fails.

**Applicable Scenarios:**

* Requires real-time authorization confirmation for transactions
* High performance requirements
* Supports multiple card BIN combinations

**Important Note:** High interface response requirements - ensure your system can complete authorization response within 800 milliseconds.

### Mode Selection Guidelines

| Dimension                | Credit Extension Mode            | Authorization Mode                 |
| ------------------------ | -------------------------------- | ---------------------------------- |
| Fund Management          | Merchant managed                 | Merchant managed                   |
| Transaction Confirmation | Fund flow synchronization        | Real-time authorization (≤800ms)   |
| System Complexity        | Medium (requires account system) | High (requires real-time response) |
| Package Management       | Platform provided                | Merchant maintained                |

***

## Pre-Integration Preparation

Complete the following preparations to ensure smooth API integration:

| Item                           | Description                                                                                                                  | Responsible Party |
| ------------------------------ | ---------------------------------------------------------------------------------------------------------------------------- | ----------------- |
| **Select Integration Mode**    | Confirm whether to adopt credit extension or authorization mode                                                              | Merchant          |
| **Apply for Merchant Account** | Contact business team for test account and corresponding `Api-Key` and `apiSecret`                                           | Business Team     |
| **IP Whitelist Configuration** | Provide server egress IP, configure to Api-Key corresponding whitelist in backend                                            | Merchant Backend  |
| **Callback URL Configuration** | Configure URL to receive transaction notifications (for card changes, consumption orders, authorization notifications, etc.) | Merchant Backend  |
| **Integrate SumSub KYC**       | Frontend integrates KYC authentication component, users complete KYC authentication through Sumsub                           | Merchant Frontend |
| **Key Management**             | Securely store `apiSecret` for encrypting/decrypting sensitive information (CVV/PIN) and signature verification              | Merchant Backend  |
| **Test Integration**           | Complete full process testing in sandbox environment (user authentication → card application → consumption, etc.)            | Merchant          |

### Complete API Basic Configuration

### Environment Information

| Environment | Domain                                      | Description                                                              |
| ----------- | ------------------------------------------- | ------------------------------------------------------------------------ |
| Sandbox     | `https://sandbox-openplatform.keysecure.io` | Test environment for development and integration testing                 |
| Production  | `https://openplatform.keysecure.io`         | Production environment, requires configuration before merchant goes live |

All examples and curl requests default to using sandbox domain. Replace with production domain for production environment.