What was the name of Twitter's live-streaming app launched in 2015?

Twitter’s live-streaming app launched in 2015 was Periscope. Twitter acquired the still-unreleased service in January 2015 and publicly launched it for iOS on March 26, 2015, amid intense interest in mobile live video and competition from Meerkat.

Periscope let people broadcast video from a smartphone while viewers watched in real time. Audiences could comment during broadcasts and send animated “hearts” as a form of appreciation. The service was built around the idea that Twitter could show events as they happened, rather than merely provide text updates about them.

Periscope grew quickly: by August 2015, it had passed 10 million accounts, and its app later arrived on Android. Twitter gradually integrated much of its live-video functionality into its own apps. The standalone Periscope apps were discontinued on March 31, 2021, but the core technology and many of its functions continued through Twitter’s live-video tools. It is sometimes confused with Meerkat, a rival service that helped spark the 2015 live-streaming race.