You have to be at least 13 years old to use Tumblr. We’re serious: it’s a hard rule, based on U.S. federal and state legislation. “But I’m, like, 12.9 years old!” you plead. Nope, sorry. If you’re younger than 13, don’t use Tumblr. Ask your parents for a Playstation 4, or try books.
— Tumblr’s Terms of Service