Ask IH: Where are all the places that professional freelancers (within any speciality) hang out online?

I'm building a product with a friend, we're finishing up the MVP design and have already started coding. It's a tool for freelancers that subcontract and contract with others. We've already got some good product fit in just explaining what the MVP does to our former colleges; They're really excited. So, I'm taking a break tomorrow afternoon to compile a list for when we're ready to release on places to share our release.

I've already started joining lots of facebook groups, linkedin groups, and different subreddits. I've found some speciality sites or already compiled them onto a list (think Indie Hackers, Hacker News, Design News, Product Hunt, and etc..).

I'd really like to find some solid non-traditional "freelancers" such as lawyers, architects, physical product designers, and etc.

Does anyone know some sites I can add?

#ask-ih