If you just need a bunch of numbers use the online credit card number generator.

Python, Java, C#, PHP and Javascript programs to generate valid credit card numbers (MOD 10). Useful for testing payment systems. This generates VISA, Mastercard, Amex, and a whole bunch of others.

Get them from darkcoding-credit-card on github, or Download (zip) all versions.

If you want to go one step further and generate a whole test identity, try the Fake Name Generator. It makes use of this credit card generator, and adds a lot of other identity data.

Note: This will only be useful to you if you know how to run a program in Python, Java, C#, PHP or Javascript. No, you cannot use this to get free things.