Tumblr has introduced sponsor packages for advertisers in its first attempt at generating substantial revenue. Packages, which start at $25,000, get advertisers access to Tumblr's 120 million daily impressions through prime spots on Tumblr Radar, which features the site's most popular posts, and Spotlight, a curated showcase of creative content. The company has no plans to require users to host third-party ads on private blogs, Tumblr tells Fast Company. "Users can host ads on their own if they wish," Tumblr spokesperson Katherine Barna says. The outlet is already a favorite of brands such as Coca-Cola and Calvin Klein, but Tumblr has resisted advertising since its inception--founder David Karp told the L.A. Times in 2010 he would rather sell the company's desks than resort to advertising.