How to Add a Payment Gateway in WHMCS
WHMCS · Self-help guide
Payment gateways allow clients to pay invoices online. In WHMCS admin, go to the payment gateway settings and activate the gateway you want to use. Enter the required API keys, merchant details, webhook settings, or credentials supplied by the payment provider. Use live keys only when you are ready to accept real payments. If the gateway supports test mode, run a test transaction first. Check that invoices show the correct payment option and that successful payments mark invoices as paid. Also review currency, tax, and callback settings. Never share payment gateway secret keys publicly or in screenshots. If payments are not updating WHMCS, check gateway logs, webhook URLs, callback settings, and fraud filters.