In German, when someone says, “Danke”, you most probably reply, “Bitte”. Easy, isn’t it?
But what do you say when someone thanks you in English? You don’t have to say anything. However, if you feel you must, then try some of these phrases:
I’m always happy to help.
Happy to help you.
I’m glad you like it.
I would avoid using ‘no problem’ or ‘not a problem’. We want to be more positive when communicating, don’t we?