How do you write you're welcome in French?

"you are welcome" (standard reply to someone saying "thank you") is translated in French (not the google automatic translation) as "de rien" or "je vous en prie". Both ways are idiomatic French, the latter being of a more elevated language level.
You can also use "il n'y a pas de quoi", or "pas de problème", which are equivalents to "no problem".