S there a Facebook tool that allows me to publish in all groups at the same time to save time since I do it with more than fifty groups?

Even if such a program existed, I would not use it or suggest it since it would result in spam in all of those groups. They will sign you in those groups since you consistently publish in an automatic and impersonal manner. So I’d really identify those 50 groups, what distinct qualities do they have, and I’d start the dialogue in a different way and on various days because there will be individuals in many of those groups who won’t find it right if you publish the same thing on all sites at the same time. Instead, distinguish the method as well as the days in the publishing schedule.