Periscope

Twitter bought Periscope in January 2015, before the app had even launched, and released it that March on top of a rival called Meerkat. It worked. Four months later Periscope had 10 million accounts. That December Apple named it iPhone App of the Year. People used it to rebroadcast a boxing match and a Game of Thrones premiere, which was the truest product-market fit it ever found. A Turkish court banned it for infringing the copyright of a Turkish company called Periskop. Twitter shut it down on March 31, 2021, citing declining usage and high maintenance costs. In 2023 Elon Musk went live and said he was using "2015 Periscope code." It showed.