Formal:
* Proszę bardzo (pro-sheh bar-dzo) - This is the most common and polite way to say "you're welcome" or "my pleasure". It literally means "please very much".
* Z przyjemnością (z pri-yem-no-sh-cho) - This translates directly to "with pleasure".
Informal:
* Nie ma sprawy (nye ma spra-vi) - This means "no problem" and is a more casual way to say "you're welcome".
* Chętnie (hen-tnye) - This means "willingly" or "gladly" and is a friendly way to respond to someone thanking you.
Other options:
* To moja przyjemność (to mo-ya pri-yem-no-sh-ch) - This is a more literal translation of "my pleasure".
The best option will depend on the situation and your relationship with the person you're talking to.