KickassTorrents (commonly abbreviated KAT) was a website that provided a directory for torrent files and magnet links to facilitate peer-to-peer file sharing using the BitTorrent protocol. It was founded in 2008 and by November 2014, KAT became the most visited BitTorrent directory in the world, overtaking The Pirate Bay, according to the site's Alexa ranking. KAT went offline on 20 July 2016 when the domain was seized by the U.S. government. The site's proxy servers were shut down by its staff at the same time.
In December 2016, former KAT staff members revived the KAT community by creating a website with its predecessor's features and appearance.
KAT was initially launched in November 2008 at the domain name kickasstorrents.com.
On 21 April 2011, KickassTorrents moved to the Philippines domain name kat.ph after a series of domain name seizures by the United States Department of Justice against Demonoid and Torrentz. The site later moved to several different domains, which the operators plan to do every six months, including ka.tt, kickass.to, kickass.so, kickasstorrents.im and kat.cr.
On 28 February 2013, Internet service providers (ISPs) in the United Kingdom were ordered by the High Court in London to block access to KickassTorrents, along with two other torrent sites. Judge Richard Arnold ruled that the site's design contributed to copyright infringement.
On 23 June 2013, KAT was delisted from Google at the request of the MPAA. In late August 2013, KAT was blocked by Belgian ISPs. In January 2014, several Irish ISPs started blocking KAT. In February 2014, Twitter started blocking links to KAT, however by the end of February 2014, KAT was unblocked on Twitter. In June 2014, KAT was blocked in Malaysia by the Malaysian Communications and Multimedia Commission for violating copyright law.
In December 2014, the site moved to the Somalia domain name kickass.so. Reports stated that it was moved as a result of site's regular domain change. On 9 February 2015, kickass.so was listed as "banned" on Whois, causing the site to go offline. Later that day, the site reverted to its former domain name kickass.to.
On 14 February 2015, it was found that messages mentioning "kickass.to" were blocked on Steam chat, but "kickass.so" and other popular torrent websites were not blocked, only flagged as "potentially malicious".
On 23 April 2015, the site moved to the Isle of Man based domain name kickasstorrents.im but was quickly taken down later that day and on 24 April it was moved to the Costa Rica based domain name kat.cr.
By July 2015, the site's kat.cr address had been removed from Google Search's results. After the removal, the top Google search result for KAT in many locations pointed to a fake KAT site that prompted visitors to download malware.
In October 2015, Portugal bypassed its courts by making a voluntary agreement between ISPs, rightsholders and the Ministry of Culture to block access to KAT and most of the other popular BitTorrent websites.
In October 2015, Google Chrome and Mozilla Firefox blocked access to KAT because of security concerns with some of the ads pointing to malware. In April 2016, Google Chrome and Mozilla Firefox blocked KAT due to phishing concerns. Both blocks were later removed after KAT dealt with the concerns.
On 20 July 2016, the United States Department of Justice announced that it had seized the KAT.cr domain and had identified its alleged owner. Artem Vaulin, a 30-year-old Ukrainian man known online as "tirm", was detained in Poland after being charged with a four-count U.S. criminal indictment. The remaining domains were taken offline voluntarily after the KAT.cr domain name was seized. Following the seizure of the original KAT domain multiple unofficial mirrors have been put online. These have no connection to the original team who have been urging users to exercise caution. A number of these mirrors have since been taken down.
Vaulin was arrested after investigators cross-referenced an IP address he used for an iTunes transaction with an IP address used to log into KAT's Facebook page. The FBI also posed as an advertiser and obtained details of a bank account associated with the site. The investigation was led by special agent Jared Der-Yeghiayan, who also tracked down Ross Ulbricht, the operator of the online black market Silk Road.
The criminal complaint, filed in the United States District Court for the Northern District of Illinois by Homeland Security Investigations, said that it was in possession of full copies of KAT's hard drives, including its email server. The investigation suggested that KAT made over $12 million per year in advertising revenue.
In late August 2016, the Department of Justice followed the complaint with a full grand jury indictment of Vaulin and two other defendants, Ievgen Kutsenko and Oleksandr Radostin; while Vaulin was still being held in Polish prison. Vaulin has both a Polish and US legal representation Ira Rothken as his lawyers to handle the allegations. In November 2016, a Polish appeals court refused to allow bail for Vaulin, stating the evidence provided by the US is sufficient to keep him in prison.
In mid-December 2016, some of the former KAT staff and moderators launched a website with a similar appearance as the original that included a small portion of the former KAT database of torrents while having a clean user database; the website's address is katcr.co to be an homage to KAT's final web address.