Tools for searching groups on Facebook

Hi, I’m looking for a tool that help me finds the groups on Facebook based on my searching words. Like when I type in the word “Gaming” in it, it will display the link to the top most result public group (based on number of members in that group)
I know FB have some policy about things like this, so I’m not sure if I can find or build one of these.
I’m new around here, so pardon me if anything I said offense you.
Thanks for your help…