How to post on multiple FB groups with least effort?

I sell used items on my Facebook marketplace and also sometimes post on fee (around 20) local FB groups i am part of.

Problem is that posting on each FB group is too time consuming and effort intensive esp when you are part of like 20 groups. And now extrapolate to this say if i have 20 listings to make of 20 products.

Is there a better way on mobile / desktop / anything else that say allows me to post simultaneously to all Selected FB groups or any other thing that allows me to make my life easier in posting these ads.

Use a third-party social media management tool like Circleboom, Social Champ, or Socinator, Buffer to connect your Facebook groups to the platform.

Is it free to use?

This is free.

No need for any too. On pc when you try to post on a group there’s a share option and it lists down all the groups you are a member of..select them and dang post at once everywhere.

I practically did that last month during an ISO as I was also in the same boat but it magically appeared and it was a bliss exp. Else I too used to manually open every group and create a new listing wasting my 1hr time.

Yes, used this but max 9 or so groups can be selected.

Isnt that sufficient? You can do 2 round if you post in 18+ groups.

Yes I will do that. Unfortunately group names are so similar, I may have to take screenshot and compare so I don’t repost to same group (chances of getting kicked out for spam).