Tumblr became available on which smartphone platform on April 17, 2010?

Tumblr became available on the BlackBerry smartphone platform on April 17, 2010.

The release was an application distributed through BlackBerry App World, Research In Motion’s software marketplace. It followed an announcement in March 2010 that Tumblr would become accessible on BlackBerry devices through an app developed by Mobelux.

This date is easy to confuse with Tumblr’s earlier iPhone history. Tumblr had already acquired the iPhone application Tumblerette in 2009, but the April 2010 milestone specifically concerned BlackBerry availability. Other mobile platforms, including Android and Windows Phone, arrived later.

BlackBerry was especially significant at the time because its smartphones were widely used for mobile email and messaging, while Tumblr was expanding beyond desktop web browsers. Tumblr itself had launched in 2007, founded by David Karp and Marco Arment, and its short-form blogging format made mobile posting a natural next step.