Reddit is a very large social media platform comprised of many general and specialist 'subreddits' aka subforums on a great many topics. There are many large transhumanist and futurist subreddits.
The is an association of subreddits unifying futurology, transhumanism and space topics.
- /r/futurology/ - Possibly the largest futurist discussion forum on the internet, default sub since May 2014, featuring 4.7 million subscribers as of December 2015. Topics are typically focused on emerging technologies
- /r/FuturistParty/ - The political organisation, the United States Futurist Party is based on this subreddit.
- /r/Transhuman/ and /r/transhumanism/ 34k subscribers between them