What did exist on Gab was a flurry of posts made by people who appeared to share Mr. Bowers’s hatred for Jews.
The site, which functions like a combination of Twitter and Reddit, is not exclusively for bigots. It has areas for various interest groups, including cryptocurrency traders, doomsday preppers and fans of Japanese-style animated pornography. In recent days, it has attracted a crowd of Brazilians who are fans of the far-right presidential candidate Jair Bolsonaro, after Facebook and Twitter took down a number of accounts that were pushing misinformation and hate speech in the country. Gab recently boasted of having 700,000 members, although it is not clear how many of those people actively use the site.
Despite its claims of pan-partisan appeal, Gab’s most popular posts espouse far-right ideology. A video about Nazi Germany appeared on the site’s “trending” section on Saturday, along with videos posted by Infowars, the conspiracy-riddled news site started by Alex Jones. Posts by the site’s members in recent days include a torrent of anti-Semitic cartoons, conspiracy theories, and denunciations of liberal censorship.
“Gab became their safe haven because it was actively recruiting the worst of the worst,” said Joan Donovan, a media manipulation researcher with the nonprofit organization Data and Society. “Gab’s users have complained of a global Jewish conspiracy to control the internet, where Gab is the only place online where they can network with one another.”
In the past several years, as Twitter and Facebook have stepped up their enforcement of policies to prevent hate speech and abuse, an “alt-tech” movement has tried to replace popular internet services with more lenient ones of its own design. None of these efforts has succeeded, and hardened white nationalists and neo-Nazis have been forced into an increasingly precarious corner of the internet, hopping between mainstream platforms as they are discovered and banned.
Discord, a chat app built for video gamers, became a haven of white nationalists last year, who used the service to plan and execute the “Unite the Right” rally in Charlottesville, Va. The company subsequently shut down several large far-right groups, but many have since reappeared.
On Saturday, a Discord channel populated by neo-Nazis filled with chatter and gossip about Mr. Bowers’s possible involvement in a mass shooting of Jews. Several members praised Mr. Bowers, while others criticized him for jeopardizing the neo-Nazi movement’s long-term prospects by resorting to violence.