How to capture credit card information to manually process later? I developed a Drupal 7 website for a client who hosts a yearly fitness expo. This year he has a competition event that requires registration and a fee.  I am looking for a way securely capture the necessary credit card and customer information to be used later to manually process the transaction.

My client has a Squareup account that he wants to use to process the transactions.  I am open to other solutions as well. While I know what Square is, I don't know anything specifically about it. Does anyone know if they offer a way for me to link to a form on their site to do what I am looking for?
Check out Commerce and Ubercart shopping carts. This is the right and best way to do this as it will save you the PCI headache as well.

However, seems that neither of the two do not have SqareUp payment integration, so you will have to do that yourself. You will have to read their API documentation and make appropriate custom module for integration.