Year it started: 2008
What it was: A "Klout Score" for users, indicating their level of social media influence. Scores ranged from 1 to 100.
Circumstances of its demise: Lithium Technologies bought Klout for $200 million in 2014. In May 2018, Lithium CEO Pete Hess announced the shutdown, saying: "The Klout acquisition provided Lithium with valuable artificial intelligence (AI) and machine learning capabilities, but Klout as a standalone service is not aligned with our long-term strategy."