You're welcome
No problem
It's nothing
It's okay
It's alright
It's all good
You're all good
No big deal
No biggie
No worries
Don't worry about it
Don't mention it
It's the least I could do
My pleasure
Happy to help
Anytime
No, thank you
Yeah of course
Yep
Don't forget you have the option to add an exclamation point (or a theoretical one at that, using your voice) to show enthusiasm! Or don't.