"Mastodon was launched as a decentralized, social justice friendly Twitter alternative that was free of Nazis and harassment. But two years later, the biggest Mastodon instance is now Gab, a far-right social media network known widely as a gathering space for white supremacists. 'Gab has always been attractive to fascist and neo-Nazi groups that advocate violence,' Joshua Fisher-Birch of the Counter Extremism Project said. 'In the past, Gab has actively promoted itself as a social media alternative when Twitter has banned extreme right groups and individuals.'"