What payment processing options are available?
Understanding payment collection for your orders
Zen Cart Authorize.net AIM Payment Module
Zen Cart Authorize.net CIM Payment Module (for card on file)
Zen Cart Authorize.net SIM Payment Module (DEPRECATED)
How are credit cards validated?
How do I authorize a Credit Card but not actually charge it until I ship the goods?
Why you shouldn’t use manual credit card processing with online stores
Payment Method problems
Consolidating PayPal accounts
Customer questions regarding paypal
PayPal Commerce, PayPal Pro, 3D Secure
Understanding the various PayPal errors
The preferred way to use PayPal in Zen Cart
Why you shouldn’t use PayPal Standard
Zen Cart PayPal Standard, Express and Pro - what’s the difference?
Resolving problems with PayPal
The original Zen Cart Square Module (DEPRECATED)
How to collect payments with Square
Preventing “OAuth access token has expired”
Handling problems with Square WebPay
How Can I Issue Store Credit instead of a Refund
Error when you return to your cart after offsite payment
Do you have a suggestion for a FAQ? Please post it to General Questions on the support forum.