What is a crypto mixer, and are mixers legal?

A crypto mixer, also called a tumbler, is a service that blends coins from many people and pays them out again so that observers cannot easily connect who sent funds to whom. Bitcoin and Ethereum record every transfer on a public ledger, so mixers are one of the main tools people use to add privacy. The same feature makes them attractive to hackers and launderers, which is why governments watch them closely.

How does a bitcoin mixer or Tornado Cash work?

Most blockchains are transparent, as explained in our guide on whether cryptocurrency can be traced. A mixer breaks the trail. Users deposit coins into a shared pool, and later withdrawals go to fresh addresses. With enough users and time, it becomes hard to tell which deposit belongs to which withdrawal.

Custodial bitcoin mixers are run by a company that takes the coins and sends them back. Tornado Cash works differently. It is a set of smart contracts on Ethereum, so users interact with code rather than handing funds to an operator. The US Treasury described it in 2022 as a service that hides the origin, destination and counterparties of transactions.

Are crypto mixers legal?

There is no single answer, and it depends on the country and on who is doing what. In the US, recent criminal cases have focused on the people who build or run mixing services, using money transmitter and money laundering laws. Our guide to crypto anti-money laundering rules covers those obligations.

Prosecutors have brought cases against operators. In November 2025, the founders of Samourai Wallet, a bitcoin privacy wallet with mixing features, were sentenced to five and four years in prison for conspiracy to run an unlicensed money transmitting business. Prosecutors said more than $237 million in criminal proceeds moved through the service.

Tornado Cash co-founder Roman Storm was convicted by a jury in August 2025 on a money transmitting charge, while the jury could not agree on money laundering and sanctions counts. As of October 2026, a retrial on those counts is set for April 2027, and his motion for acquittal was still pending, according to The Block.

Is Tornado Cash still sanctioned?

No. As of October 2026 Tornado Cash is not on the US sanctions list. Treasury's Office of Foreign Assets Control sanctioned it in August 2022, saying it had been used to launder more than $7 billion since 2019, including over $455 million stolen by North Korea's Lazarus Group. On March 21, 2025, Treasury lifted those sanctions, citing new legal and policy questions about sanctioning changing technology.

Treasury also said it remains deeply concerned about North Korean hacking and laundering, and it warned US persons to be cautious with transactions that could benefit such actors. Rules differ by country and change often. Check the regulator or a qualified professional for your own situation.