> ## Documentation Index
> Fetch the complete documentation index at: https://developer.gcashier.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Cross-Border Payment API for SMEs

> Gcashier Pay provides a secure, API-driven cross-border payments platform for collection, currency exchange, international remittance, and payouts.

Gcashier Pay gives your business a single integration point for the full cross-border payment lifecycle — from merchant onboarding and virtual account collection to FX trading, international remittance, and withdrawals. Every request is encrypted end-to-end using AES and RSA, and all asynchronous events are delivered via webhook callbacks to your platform.

<CardGroup cols={2}>
  <Card title="Quickstart" icon="bolt" href="/quickstart">
    Make your first API call in minutes — set up keys, encrypt a request, and verify the response.
  </Card>

  <Card title="Authentication" icon="key" href="/authentication">
    Learn how RSA keys and AES session encryption work together to secure every API call.
  </Card>

  <Card title="API Reference" icon="code" href="/api/merchant/access-application">
    Full reference for all 40+ endpoints across merchant access, collection, FX, payments, and accounting.
  </Card>

  <Card title="Guides" icon="book-open" href="/guides/merchant-onboarding">
    Step-by-step walkthroughs for onboarding, collection, currency exchange, and international transfers.
  </Card>
</CardGroup>

## What You Can Build

<CardGroup cols={3}>
  <Card title="Collections" icon="arrow-down-to-line" href="/guides/collection">
    Open virtual accounts and receive payments from customers worldwide.
  </Card>

  <Card title="FX & Exchange" icon="arrows-rotate" href="/guides/currency-exchange">
    Get real-time quotes and execute currency conversions programmatically.
  </Card>

  <Card title="International Transfers" icon="globe" href="/guides/international-transfers">
    Send cross-border remittances to beneficiaries in supported countries.
  </Card>

  <Card title="RMB Payments" icon="yin-yang" href="/api/payments/rmb-payment">
    Initiate domestic CNY payments to Chinese bank accounts.
  </Card>

  <Card title="Payouts" icon="money-bill-transfer" href="/guides/payouts">
    Withdraw settled funds to your linked bank account.
  </Card>

  <Card title="Accounting" icon="chart-line" href="/api/accounting/balance-inquiry">
    Query account balances and full transaction history in real time.
  </Card>
</CardGroup>

## How It Works

<Steps>
  <Step title="Onboard your merchant account">
    Submit your merchant KYC details via [sp1101](/api/merchant/access-application). Gcashier Pay reviews your application and activates your account.
  </Step>

  <Step title="Exchange RSA public keys">
    Generate a 2048-bit RSA key pair, share your public key with Gcashier Pay, and receive Gcashier Pay's public key in return. These keys secure every API message.
  </Step>

  <Step title="Integrate and test">
    Use the sandbox environment to test your integration with [mock endpoints](/api/reference/mock-testing). Validate encryption, signing, and webhook delivery.
  </Step>

  <Step title="Go live">
    Provide your production server IP, exchange production RSA keys, and switch your base URL to the production environment.
  </Step>
</Steps>

<Note>
  All API requests use **HTTPS 1.2** with JSON payloads. Messages are AES-encrypted and RSA-signed — see [Encryption & Signing](/concepts/encryption-signing) for the full specification.
</Note>