Whirlpool mixing volume tops $10M amid mobile use

Samourai Wallet’s Whirlpool coin-mixing volume has surpassed $10 million worth of bitcoin, with roughly 40% of the total added in the prior month, according to the Whirlpool Stats Tool. The figures cover activity through late March 2020, and early April readings pointed to continued growth.

Whirlpool is a non-custodial implementation of Chaumian CoinJoin, a method that combines multiple users’ Bitcoin transactions into uniform outputs to make them harder to trace on the public blockchain. The service is integrated into Samourai’s mobile wallet, with a desktop option available, and organizes activity into multiple liquidity pools by unspent transaction output (UTXO) size. Whirlpool uses a one-time flat fee per UTXO rather than volume-based pricing.

Samourai presents Whirlpool as an optional privacy layer that does not require giving up control of funds. The company describes Whirlpool as a tool that “breaks the link of your bitcoins and their prior history and stops blockchain analysis in their tracks,” and promotes a “mobile first experience.”

Usage accelerated in early 2020. Data from the Whirlpool Stats Tool indicates cumulative volume reached about $10 million in bitcoin by late March, with more than 1,500 BTC mixed by that time. The tool, which updates continuously, showed a strong month-over-month increase into early April.

Interest in mixing has grown alongside wider awareness that bitcoin transactions are public and can be analyzed. CoinJoin techniques, first proposed in 2013, aim to make it more difficult to connect transaction inputs and outputs. Whirlpool standardizes output amounts and can cycle UTXOs through repeat mixes, which can expand the anonymity set over time.

The recent pickup follows a challenging period for third-party mixers. In 2019, law enforcement actions in multiple jurisdictions led to the shutdown of several long-standing services, particularly in Europe. Those disruptions steered privacy-focused users to wallet-based options, where mixing is an opt-in feature and custody remains with the user.

Activity in alternative privacy tools outside the Bitcoin network increased as well. Users of Bitcoin Cash tested CashFusion, a CoinJoin-style approach for that network, reporting positive feedback and fundraising progress during its alpha phase in early 2020.

Whirlpool’s operators point to a combination of non-custodial architecture, flat-fee pricing, smartphone access and multiple pool sizes as factors that lower barriers for users who choose to mix their coins.