WHMCS IntegrationCopy Anchor Link

The PayzCore WHMCS module adds USDT/USDC blockchain monitoring as a payment method for invoices in your WHMCS installation. It is installed as a WHMCS payment module; PayzCore itself only watches the blockchain and notifies WHMCS.

• Marketplace: WHMCS Marketplace
• Source: github.com/payzcore/whmcs
• Requirements: WHMCS 7.x+, PHP 7.4+, PayzCore account

How It WorksCopy Anchor Link

1. Client views an unpaid invoice and clicks "Pay with USDT/USDC".
2. WHMCS module calls the PayzCore API.
3. Payment page shows the wallet address, QR code, and exact amount.
4. Client sends stablecoins from their wallet.
5. PayzCore sends a webhook to callback.php.
6. Module verifies the HMAC signature and applies the payment to the invoice.
7. Invoice is marked as "Paid".

InstallationCopy Anchor Link

1. Download the module from the WHMCS Marketplace or from the GitHub repository (Code > Download ZIP)
2. Copy the files into your WHMCS installation:

your-whmcs/modules/gateways/
├── payzcore.php                  ← Main module file
├── payzcore/
│   ├── PayzCoreApi.php           ← API client
│   └── hooks.php                 ← Optional admin hooks
└── callback/
    ├── payzcore.php              ← Webhook receiver
    ├── payzcore_poll.php         ← Status polling for the invoice page
    └── payzcore_confirm.php      ← Tx hash submission (pool + txid mode)

3. (Optional) For blockchain explorer links on admin invoices, copy modules/gateways/payzcore/hooks.php to includes/hooks/payzcore.php
4. Set correct file permissions (644 for files, 755 for directories)

ConfigurationCopy Anchor Link

1. In WHMCS admin: Setup > Payments > Payment Gateways
2. Open the All Payment Gateways tab, find PayzCore (USDT/USDC) and click Activate
3. Configure the settings:

4. Click Save Changes. The module calls GET /v1/config (and caches the result) to detect the networks and tokens of your connected wallet. Clients choose from these on the invoice page; no manual selection is needed.

5. Set your webhook URL in the PayzCore dashboard to:

https://yourdomain.com/modules/gateways/callback/payzcore.php

Invoice Status MappingCopy Anchor Link

Overpayment HandlingCopy Anchor Link

When a client overpays, the invoice is marked as Paid and the overpayment amount is logged in the WHMCS transaction notes. Refunds or credits must be handled manually by the admin.

Partial Payment HandlingCopy Anchor Link

If a client sends less than the invoice amount, the received amount is applied as a partial payment. The invoice remains open for the remaining balance. The client can create a new payment for the remainder.

Client ExperienceCopy Anchor Link

1. Client views an unpaid invoice in the WHMCS client area
2. Selects "Pay with USDT" (or your configured display name)
3. Sees the wallet address, QR code, exact amount, and expiration timer
4. Sends the exact stablecoin amount from their wallet
5. Once confirmed, the invoice status updates automatically

TroubleshootingCopy Anchor Link

Module not showing in adminCopy Anchor Link

• Ensure all files are in the correct directories (see Installation)
• Check PHP error logs for syntax errors
• Verify file permissions (readable by web server)

Callback not workingCopy Anchor Link

• Verify the callback URL is accessible from the internet: https://yourdomain.com/modules/gateways/callback/payzcore.php
• Check that your server allows POST requests from external IPs
• Look for errors in the WHMCS Activity Log: Utilities > Logs > Activity Log

Invoice not updating after paymentCopy Anchor Link

• Confirm the Webhook Secret matches between PayzCore and WHMCS settings
• Check the WHMCS Gateway Log: Utilities > Logs > Gateway Log
• Verify the PayzCore webhook delivery status in your PayzCore dashboard

See AlsoCopy Anchor Link

• Getting Started - Account and project setup
• Webhooks Guide - Events, headers, and signature verification
• Supported Networks - Available networks and tokens
• Error Reference - HTTP status codes and troubleshooting