After Yahoo spent $990 million to acquire the social blogging platform in May 2013, its traffic appeared to stall on a plateau, leading some critics to question Marissa Mayer’s investment.

But new data from Global Web Index shows a revival in Tumblr’s momentum. In the last six months, it experienced a remarkable 120 percent jump in active users, making it the fastest growing social network — topping YouTube, Pinterest, Twitter and Instagram. Although the largest social service in the world, Facebook is now the slowest-growing of the bunch, with only 2 percent growth in active users.