Harry Knowles started Ain't It Cool News in his Austin bedroom in 1996. The Hollywood Reporter wrote in 2013 that a back injury on January 24, 1996, suffered while helping his father pack up after a memorabilia show, left him at home, where he chased movie news online after supplying weekend box-office figures to the Drudge Report. He named the site after a John Travolta line in Broken Arrow and invited people in the industry to send tips, promising never to reveal their identities.
Those tipsters, whom Knowles called spies, sent casting news, set reports and reviews of test screenings. Coverage of the 1997 Star Wars Special Edition re-release drove a traffic spike. In June 1997 Sony sent a cease-and-desist demand over Starship Troopers production art, and Knowles replaced the art with the letter. Warner Bros. marketing head Chris Pula criticized the site in The New York Times and People, and the studio blamed bad word of mouth from Knowles's team for the performance of Batman & Robin. Peter Jackson later used the site for an open Q&A with fans of The Lord of the Rings.
In Austin, Knowles became tied to the Alamo Drafthouse. Starting in 1999 it hosted his Butt-Numb-A-Thon, a 24-hour birthday marathon of old and unreleased films, and in 2005 he and Tim League were among the co-founders of Fantastic Fest. Drew McWeeny, who wrote for the site as Moriarty, told THR that Knowles "almost by force of will, made Austin the film mecca it is now."
THR reported in 2013 that advertising revenue had fallen from about $700,000 a year in the early to mid-2000s to the low six figures by 2012, that the site owed about $300,000 in back taxes, and that it drew about 300,000 unique visitors a month.
On September 23, 2017, IndieWire reported that Jasmine Baker said Knowles groped her at Drafthouse events in 1999 and 2000. Knowles told IndieWire, "I categorically deny it." AICN had already withdrawn as a Fantastic Fest sponsor. On September 25, Eric Vespe (Quint), Steve Prokopy (Capone) and Horrorella left the site, and the Alamo Drafthouse said it had severed all ties with Knowles. On September 26, IndieWire published accounts from four more women, and Knowles announced a leave of absence, handing the site to his sister. Slate reported in 2022 that he had returned in March 2020 with a public apology and that the site was updated a few times a week. It was still posting new interviews in October 2026.