Tumblr
Tumblr is a social media platform that gained popularity in the 2010s. Users maintain blogs (potentially multiple per account) that allow them to publish original posts as well as "reblogging" others' posts. Reblogs function similarly to Twitter's "retweet" function but allow optional additions to the post body (which are displayed under the original posts) or to tags (displayed only on the reblogger's blog). This allows multiple discussions to branch off from an original post.
Culturally, Tumblr is extremely popular with LGBTQ people and hosts a wide range of content related to non-binary issues. Many pieces of non-binary language and iconography originated on Tumblr, and there are a large number of single-issue blogs that center on non-binary issues. It is also common for Tumblr users to list their pronouns and gender identities on their blogs.