Mixer / Tumbler

Cryptocurrency mixers (also called tumblers) accept deposits from multiple users, combine them, and return equivalent amounts minus a fee from different wallet addresses, breaking the on-chain link between sender and recipient. Decentralised versions use smart contracts (such as Tornado Cash) to achieve the same obfuscation without a central operator.

While mixers have privacy use cases, they are heavily used by cybercriminals to launder stolen cryptocurrency after hacks, rug pulls, and ransom payments. Receiving funds that have passed through a mixer can implicate a recipient in money-laundering even if they were unaware of the source. Several mixer operators and associated smart contracts have been sanctioned by regulators.

For consumers, the risk is primarily reputational and legal: accepting payment through a mixer, even unknowingly, can result in having funds frozen by an exchange's compliance system. Scam victims are sometimes directed to mixers by fraudsters claiming to "protect" the recovery process, which is a red flag that the supposed helper is complicit.