Wasabi Wallet, Whirlpool and JoinMarket: operational models, decentralization, costs, usability and waiting times to increase the privacy of your UTXOs.
CoinJoin is a trustless technique for Bitcoin users who want to improve the privacy of their UTXO. It is a methodology that allows multiple users to combine their UTXO into a single transaction, breaking the deterministic links between old UTXO and new ones. The concept of coinjoin was first proposed in 2013 by developer Gregory Maxwell. Among the main solutions currently available are Wasabi Wallet, Whirlpool (relaunched by Ashigaru) and JoinMarket. Although all implement the CoinJoin protocol, each adopts a different approach in terms of operational model, decentralization, costs and ease of use.
Wasabi Wallet
Wasabi Wallet is an open source desktop wallet that implements the WabiSabi protocol, allowing coinjoin transactions with variable amounts. This aims to reduce the creation of “toxic change”, allowing exact change or no change. The WabiSabi protocol is designed to be “trustless”, which means the coordinator cannot steal funds or violate the privacy of participants. All communications and transactions are routed through the Tor network, which encrypts internet traffic and hides users’ IP addresses. Thanks to client-side block filters (BIP-158), the wallet obtains transaction history without exposing users’ addresses to external servers. In practice, Wasabi downloads only part of a block and, in case of a match, requests the complete block directly from random Bitcoin nodes on the P2P network, using Tor to further obfuscate users’ identity and activity.
Historically, Wasabi’s coordinator was managed by zkSNACKs Ltd., the company that sponsored the development of Wasabi Wallet. The use of a centralized coordinator created a single point of failure and regulatory vulnerability. This tension culminated in zkSNACKs’ decision to discontinue its coordination service in June 2024, citing increased regulatory pressure following the arrest of Samourai Wallet founders. However, the community responded with the emergence of alternative and independent coordinators like Kruw, which helped diversify the ecosystem, making it less vulnerable to regulatory pressure.
List of existing coordinators on Wasabi Wallet.
Operational model and decentralization
Wasabi Wallet uses a centralized approach with a single coordinator, which however does not know the input and output flows thanks to the implementation of blind signatures and connection via Tor. The wallet is designed to be entirely automatic: the user configures their mixing strategy and lets the software work. No manual intervention is required during the process nor is it possible to manually select which coins to mix.
Fees and costs
From version 2.2.0.0 onwards, Wasabi Wallet has eliminated its own fees. Currently Wasabi users pay only mining fees for the block space used, relying on voluntary or alternative coordinators. New coordinators, like Kruw, can implement their own fee structures, with some offering coordination for free.
Mixing strategies, such as “Default Strategy”, “Reduce costs” or “Enhance privacy”, also help calibrate expenses, optimizing times and costs depending on network peaks. For example, the “Reduce costs” strategy starts coinjoin rounds only when network fees are low.
Mix size and waiting times
Wasabi Wallet allows participation in multiple mixes with UTXO of different sizes. The resulting outputs are of different sizes from each other. For example, the Wasabi website lists dozens of possible values generated in a round (from 0.00005 BTC up to thousands of BTC).
A 2024 report found an average of 60.6 participants per round, with average inputs of 0.36 BTC and about 36.9 rounds per day. Waiting times can vary from a few hours to a maximum of a few days to achieve the desired privacy.
Technical requirements
Wasabi is available on desktop (Windows, Mac, Linux); there is no mobile app. To further improve privacy, the wallet can be connected to your own Bitcoin full node.
Whirlpool (Ashigaru)
Whirlpool, originally part of Samourai Wallet and now relaunched by Ashigaru, is an implementation of Zerolink coinjoin.
The Whirlpool workflow is two-phase: first the user generates an entry transaction (Tx0) depositing up to 20 UTXO into one of the two available pools, paying a fixed anti-Sybil fee; subsequently the user participates in the actual mixing rounds.
The “pre-mixing” transaction (Tx0) separates excess change from UTXO destined for mixing and from coordinator fees before coinjoin, ensuring that “toxic change” outputs are not created directly from the mix. After the initial mix, users can participate in “remixing” rounds for free. This allows already mixed outputs to join additional rounds, increasing their anonymity set without incurring additional service fees.
Operational model and decentralization
Ashigaru Whirlpool relies on a central coordinator that cannot track inputs and outputs thanks to the use of blind signatures and connection exclusively via Tor. However, compared to Wasabi, Whirlpool requires greater manual intervention from the user. The procedure begins with generating a premix transaction (Tx0), necessary to access one of the available pools. From there on, coinjoin rounds happen automatically.
The new system uses an Electrum server as backend, eliminating the dependency on Dojo nodes and making the solution compatible with platforms like Start9, Umbrel and myNode. This architectural change also ensures that the Ashigaru team does not have access to users’ master public keys (xpub).
The code is open-source and designed to allow the creation of various independent coordinators.
Fees and costs
Whirlpool applies a 5% anti-Sybil fee on the pool value (0.25 BTC and 0.025 BTC pools) at entry through the Tx0 transaction. After the initial payment, there are no additional fees for each round, excluding the cost of normal network fees. This model aims to discourage Sybil attacks and ensure greater security for participants.
Mix size and waiting times
Mix outputs are equal to the chosen pool value, with fixed sizes (e.g. 0.25 BTC for the main pool). There are no “multiple denominations” like in Wasabi. Waiting times depend on the number of participants. Once Tx0 is completed, mixes activate randomly at regular intervals.
Technical requirements
To use Whirlpool, the compatible Ashigaru Terminal interface is required, a Terminal User Interface application available for desktop. The use of a Bitcoin full node is recommended. The interface may be less intuitive compared to Wasabi.
JoinMarket
In 2015 Chris Belcher announced JoinMarket, the first implementation of the CoinJoin protocol. JoinMarket stands out for its completely decentralized and peer-to-peer model.
JoinMarket operates through a “maker-taker” market model:
- maker: offer liquidity by creating partially signed transactions and making their UTXO available to be mixed. In exchange for this service, they earn a commission;
- taker: initiate coinjoin transactions and pay a commission to makers for the service. Fees are not fixed but are determined by the market, based on demand and supply.
The protocol is open-source and trustless: each user always holds their private keys and signs their inputs in the coinjoin.
Operational model and decentralization
Unlike Wasabi and Whirlpool, there is no central coordinator: the meeting between makers (who provide liquidity) and takers (who want to participate in coinjoin) happens through a peer-to-peer protocol. This ensures total independence from central servers and more flexible management. Participating nodes communicate with each other via Tor.
If a user decides to act as a maker, they can set up a Fidelity Bond to attract users to choose them as a collaborator in a coinjoin transaction. The concept of Fidelity Bond was introduced in the JoinMarket protocol as a system to ensure that market actors act honestly. It is a primary mechanism for Sybil attack resistance, making it economically expensive for an attacker to control multiple identities.
The Fidelity Bond is a function that allows locking a certain amount of bitcoin to show the network one’s commitment (reputation) in using the protocol. It is important to lock a certain amount of bitcoin if you want other taker users to consider and accept the offer. The locked bitcoins are impossible to move until the bond expires. It should be noted that without a Fidelity Bond it might be more difficult for your offer to be chosen. The protocol is particularly appreciated by expert users, as it allows maintaining maximum control over one’s UTXO. However, configuration is more complex and requires more advanced knowledge.
Fees and costs
JoinMarket does not apply its own fees. Costs depend on rates determined by makers, which can vary based on demand. These costs, combined with normal network fees, are generally competitive, making JoinMarket an economically advantageous option for users.
Mix size and waiting times
JoinMarket supports mixes of any size above the dust limit, provided there are makers available to satisfy requests. Mixes can involve 4 to 20 counterparties, with almost immediate times for takers. However, makers must wait for a taker’s request to complete the process. The resulting anonymity depends on the number of rounds executed.
Technical requirements
JoinMarket is primarily designed to be used from command line on computers connected to a Bitcoin full-node. However, optional graphical interfaces exist, such as JoinMarket-Qt and Jam, which greatly simplify its use.
