Within two weeks of its February 2007 launch, Tumblr had gained 75,000 users.
Tumblr grew out of David Karp’s interest in “tumblelogs,” short-form blogs built around quickly sharing links, photos, quotations, and other media. During a gap between consulting contracts in 2006, Karp and developer Marco Arment began building the service at Karp’s company, Davidville. Tumblr opened to the public in February 2007 and attracted an unusually large early audience almost immediately.
The figure refers to users gained during the first two weeks, not Tumblr’s total lifetime audience or its number of posts. That distinction matters because later reports used much larger measurements, including monthly visitors, registered users, and daily posts. The tempting alternatives in this quiz—25,000, 150,000, and 1 million—belong to no comparable milestone in Tumblr’s launch story.
Tumblr’s early traction helped establish it as a major microblogging platform before Yahoo acquired it in 2013. Its format combined blogging’s personal publishing with social-network features such as following and reblogging.