It might be already requested before but it doesn't seem to be here...

Could GOG please make a filter on the games page (https://www.gog.com/games?sort=bestselling&page=1) where the games I own are not shown anymore? I own a lot of games here on GOG so it would be nice to reduce the number of pages by filtering out the games I own already.

Or is there already something like that? :) If not: please GOG make it happen! ;)

There is a Wishlist Entry for it, at least.
Meanwhile, you could give Barefoot Essentials a try, which does include that feature and some other neat things.

Thank you for your response! I voted for the wishlist entry and I'll look into the barefoot essentials! :)