The social network Gab has attracted many far-right users, including Robert Bowers, the suspected Pittsburgh synagogue shooter.
The man who allegedly opened fire in a Pittsburgh synagogue Saturday morning, killing 11 people and injuring six, was reportedly a frequent poster on Gab, a relatively new social network that has attracted many from the far-right fringe.
Robert Bowers, the suspected shooter, reportedly joined Gab at the beginning of this year, using it to post a series of anti-Semitic messages and redistribute many more from other users. Immediately before he allegedly attacked the synagogue, Bowers took aim at HIAS, a Jewish organization that helps refugees.
"HIAS likes to bring invaders in that kill our people," he wrote, according to an archive of his Gab posts. "I can't sit by and watch my people get slaughtered. Screw your optics, I'm going in.
Read more: Here's what we know about Robert Bowers
Gab, which bills itself as the free-speech alternative to Facebook and Twitter, has become a haven for far-right extremists. The site does not police hate speech, instead encouraging users to take advantage of its tools to filter out posts they find offensive.
Here's what we know about Gab:
Gab was launched in August 2016.
Initially, consumers could only use the site if they'd been invited to register.
The site was cofounded by Andrew Torba.
Torba founded Gab with Ekrem Büyükkaya, with whom he'd worked at AutomateAds.com.
Torba launched Gab as an alternative to Facebook and Twitter.
Torba told BuzzFeed News he had been frustrated with the way "left leaning Big Social" sites were filtering posts, feeling like they weren't qualified to judge what was news or harassment.
"It didn't feel right to me, and I wanted to change it, and give people something that would be fair and just," he told BuzzFeed News.
Torba touts Gab for its commitment to free speech.
Gab's guidelines prohibit users from posting certain kinds of things, such as threats of violence, illegal pornography, and other users' private information, without their consent.
But it generally doesn't bar posts that many might consider abusive or hateful. Instead, it offers features that allow users to filter out offensive posts.
The site quickly became a popular hangout for white supremacists.
Gab has an open-door policy for far-right figures like Milo Yiannopoulos and Alex Jones, who have been kicked off of Twitter and other tech platforms.
Although the site purports to be open to anyone who shares "in the common ideals of Western values, individual liberty, and the free exchange and flow of information," it's most frequently populated by far-right ideologies.
The service is relatively small.
As of the beginning of September, Gab had 635,000 registered users, according to a document it filed with the Securities and Exchange Commission. That's up from just 394,000 in March, but it's a drop in the bucket compared to the social-media giants.
By comparison, Twitter has some 326 million monthly active users, including 67 million in the US, and Facebook has some 2.2 billion users a month around the world, including 185 million in the US and Canada.
Gab's run into trouble before.
In August, Microsoft threatened to kick Gab off of its Azure cloud computing service for hosting posts that advocated genocide against Jews. The author of the posts later deleted them.
Gab ran into a similar problem last year, when its domain registrar, responding to anti-Semitic threats, threatened to seize its domain if it didn't find a new host.
In 2016, Apple blocked Gab from its App store, citing pornographic content and hate speech.
Google also blocked the app from its Google Play store for hate speech.
After the Pittsburgh shooting, PayPal announced it was dropping the company.
Gab's Twitter account was defensive after the shooting, posting dozens of tweets about free speech and responding directly to critics.
Gab also posted an official statement condemning "all acts of terrorism and violence" and said it was cooperating with authorities.
The site posted an official statement on the shooting:
"Gab.com's policy on terrorism and violence have always been very clear: we a have zero tolerance for it. Gab unequivocally disavows and condemns all acts of terrorism and violence. This has always been our policy. We are saddened and disgusted by the news of violence in Pittsburgh and are keeping the families and friends of all victims in our thoughts and prayers.
"We refuse to be defined by the media’s narratives about Gab and our community. Gab's mission is very simple: to defend free expression and individual liberty online for all people. Social media often brings out the best and the worst of humanity."