Je vous en prie
To clarify things, 'you are welcome' if said in response to thanks, translates as "Je vous en prie" or "Je t'en prie" (see Alix's explanations of when to use which).
In informal conversation, one could also use "de rien" or "pas de quoi".
"Welcome" literally translates as "bienvenue" and I believe that in Canadian French this can also be used after thanks, like the English 'you're welcome'.
If, however, you wanted to use 'you are welcome' as part of a sentence, the translation would be different:
'you are welcome to use my car' = 'tu peux prendre ma voiture si tu veux'
'you are welcome to come back at any time' = 'tu reviendras quand tu voudras'
'you are always welcome here' = 'tu seras toujours le (la) bienvenü(e) ici'.
Local time: 15:37
Native speaker of: English, French
PRO pts in pair: 932