What are the most active private groups of entrepreneurs?

I'm the cofounder of https://www.joinsecret.com. Entrepreneurs save with Secret thousands of dollars on software (deals with AWS, Airtable, Pipedrive, etc.). It's 100% free.

Our users love what we do (who does not want to save money when you grow your startup?) and we are looking for additional ways to spread the word of Secret in local entrepreneurial communities.

Hence I have 3 questions: 1/ what are the most active private Facebook/Telegram/other social media groups for tech entrepreneurs? 2/ what are the most active private slack groups for tech entrepreneurs? 3/ what are the most active forums for tech entrepreneurs (outside of Reddit/IH)?

I guess based on your feedback I could also build a sheet that would be beneficial to more entrepreneurs. And feel free to add groups that exist outside of these networks :) Thanks a lot for your help!