Tornado Cash (also stylized as TornadoCash) is an open source, non-custodial, fully decentralized cryptocurrency tumbler that runs on Ethereum Virtual Machine-compatible networks.

[citation needed] Tornado Cash was created in 2019, and was alleged by the U.S. Department of the Treasury to have been "used to launder more than $96 million of malicious cyber actors’ funds derived from the June 24, 2022 Harmony Bridge Heist".

[5] On 8 August 2022, the Office of Foreign Assets Control of the U.S. Department of the Treasury blacklisted Tornado Cash, making it illegal for United States citizens, residents, and companies to receive or send money through the service.

On May 26th the hacker effectively relinquished control, but had converted a portion of the stolen governance tokens to Ether valued at around $900,000, and laundered them through the service.

[20] On November 26, 2024, the United States Court of Appeals for the Fifth Circuit ruled that the immutable smart contracts used by Tornado Cash do not qualify as "property" under federal law, and that the Office of Foreign Assets Control lacked authority to sanction Tornado Cash software directly, "as opposed to the rogue persons and entities who abuse it".