Formal:
* À plus tard: This is the most common and neutral way to say "until later." It's appropriate for most situations.
Informal:
* À tout à l'heure: This literally means "until later" but is often used when you'll see the person again soon.
* À bientôt: This literally means "see you soon" and is a more casual way to say goodbye.
* On se retrouve plus tard: This literally means "we'll meet later" and is a more informal way to say goodbye.
Note: The choice of expression depends on the situation and your relationship with the person.
Here are some examples:
* "I'll see you later." - À plus tard.
* "I'll see you soon." - À tout à l'heure.
* "See you around." - À bientôt.
* "Let's meet later." - On se retrouve plus tard.