This plug-in can be embeded into your webshop checkout page, using the existent card form.
Its aim is to help the user finding the card info that your checkout page would require (source code).

It may be used in tandem with a card validator class that would help validating the card info and guessing the card brand (which I did herein).

Please enter some dummy card information to test the way this plug-in works. DO NOT use any real card number! However, no data is collected or transmitted remotely, but anyway...
Btw: PayPal provides some test credit card account numbers :-)