[1][2] Social media influencer Liora Rez founded StopAntisemitism as StopAntisemitism.org in October 2018 to monitor and expose online antisemitism.

[8] StopAntisemitism receives real-time tips about antisemitic incidents via its website and social media accounts.

[10] A defamation and invasion of privacy lawsuit against the organization by a former university professor who had been named "Antisemite of the Week" was dismissed by a Pennsylvania court, which found that the organization's claims are "matters of opinion...subject to disagreement and do not imply the presence of undisclosed facts" and are protected by the U.S. Constitution's First Amendment.

[11][12] In October 2019, StopAntisemitism sent a petition with 2,000 signatures to the US Department of Education calling on the agency to keep the Council on American–Islamic Relations (CAIR) out of college campuses.

[16] Journalist Jonathan Tobin lauded StopAntisemitism for carrying forward the education effort of established civil rights groups, such as the Anti-Defamation League.

As a result of her work with StopAntisemitism, Rez was chosen by the Algemeiner newspaper for its "J100" list of "The Top 100 People Positively Influencing Jewish Life":[5] in 2019,[6] 2021,[17] and 2022.