Pretty much every reasonable payment processor out there will have a “test” mode, where you can enter test transactions that will work just like the real system, but don’t require real credit cards and don’t result in real charges.
To do this, you’re going to need some test credit cards to use. A simple search will turn up several pages that will help. However, here are the ones I use the most:
|Visa||4111 1111 1111 1111|
|(It can be any month in the future.)|
|MasterCard||5555 5555 5555 4444|
|all other info is the same as Visa|
Some payment processors will generate all their different response codes based on a particular amount you send for the test transaction. Pretty clever.