À bientôt
This is a very versatile phrase and can be used in a variety of situations.
Here are some other options, depending on the context:
* On se voit bientôt: "We'll see each other soon" (slightly more formal)
* À tout à l'heure: "See you later" (implies a shorter timeframe)
* On se retrouve bientôt: "We'll meet again soon" (implies a planned future meeting)
You can also use the phrase à plus tard which means "see you later" but it is considered more informal.