Payment Authorization

PayPal Express Checkout Integration

Setting up PayPal Express Checkout

Restricting payment methods to PayPal only

Using PayPal for standalone donations

Auditing PayPal payments

Refunding PayPal payments

Authorizing Credit Cards in iMIS

Setting up card authorization

Using card authorization

Authorization Gateways

Applying for a merchant bank account

Implementing Payflow Pro as an authorization gateway

Implementing SafePay as an authorization gateway

Creating a custom credit card gateway

More:
PayPal Express Checkout Integration
Authorizing Credit Cards in iMIS
Authorization Gateways