SWAT police officers respond after a gunman opened fire at the Tree of Life synagogue in Pittsburgh, Pennsylvania, U.S., October 27, 2018. REUTERS/John Altdorfer

(Reuters) - Alleged Pittsburgh synagogue shooter Robert Bowers used the web site Gab.com to express anti-Semitic views. Here is some information about the site, which said it suspended his account and contacted the authorities after the arrest.

** Gab launched in 2016 as a “free-speech” alternative to Twitter. Its founder, Andrew Torba, said existing sites like Twitter and Facebook have a left-leaning monopoly on social media. It allows users to read and write unfiltered messages of up to 300 characters, called “gabs”

** The home page describes the platform as “a social network that champions free speech, individual liberty and the free flow of information online. All are welcome.”

** Gab is a popular gathering place for alt-right activists and white nationalists whose views are unwelcome or banned on other social media platforms. Early members included the right-wing provocateur Milo Yiannopoulos and Andrew Anglin, the founder of the neo-Nazi Daily Stormer website. Other well known users have included controversial media personalities Alex Jones and Carl Benjamin.

** PayPal advised Gab on Saturday that it was banned from using the company’s money sending services.

** Apple blocked the app from its App store in 2016, citing pornographic content, and later, hate speech. Google blocked the app from its Google Play store for hate speech, which brought a law suit from Gab that was eventually dropped.

** The company defended itself from criticism on Saturday, saying “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.”