CoinJoin

A CoinJoin combines inputs from multiple users into a single tx with multiple equal-amount outputs to defeat the common-input- ownership heuristic that chain analysts use.

Heuristic broken

Pre-CoinJoin: chain analysts assume "all inputs of a tx belong to the same wallet". This is true for most txs.

CoinJoin breaks this: 10 users, each contributing 1 input, 10 outputs of equal size. Analyst can't link any specific input to any specific output.

Major implementations

Wabisabi (Wasabi Wallet 2.0)

Coordinator-mediated with credential-based blinding.
Users register inputs with the coordinator privately (blind sig).
Anonymity within the round; coordinator can't link inputs to outputs.
Wasabi 2.0 uses WabiSabi protocol — successor to ZeroLink.
Default round: ~50 participants; output amounts in tiered denominations.

Whirlpool (Samourai, relaunched by Ashigaru)

Coordinator-mediated ZeroLink. Samourai shut down 2024 (US indictment April 2024); the founders were sentenced in November 2025 — see Legal outcome.
Used 5x equal-output structure.
Not dead: the Ashigaru Open Source Project (anonymous Samourai fork) relaunched a ZeroLink coordinator on 23 June 2025, together with Ashigaru Terminal v1.0.0, a Sparrow-derived desktop client for Linux/macOS/Windows. Tor-only, no clearnet.
Ashigaru pools as of mid-2026: 0.025 BTC and 0.25 BTC, each with a 5% anti-Sybil fee charged on the Tx0 entry transaction (max 20 premix UTXOs per Tx0); remixes are free and unlimited.

JoinMarket

Maker/taker model:
- Makers offer liquidity passively, earn small fees.
- Takers initiate CoinJoins, pay makers.
No central coordinator — IRC + onion services.
Slower / smaller anonymity sets but censorship-resistant.
Two wire-compatible implementations share one order book as of September 2026: the reference joinmarket-clientserver (archived 27 Apr 2026, final release v0.9.12) and joinmarket-ng, which is the actively developed one. Target NG for new work.

Privacy properties

After CoinJoin, the linked inputs:

Have equal anonymity-set among the participants.
Subsequent tx that mixes them can re-cluster (if you spend two CoinJoined outputs together, observer infers same wallet).

Crucial: maintain post-CoinJoin hygiene:

Don't combine CoinJoined outputs with non-CoinJoined ones.
Don't reuse addresses.
Don't immediately spend (timing analysis).

CoinJoin types

Equal-output ZeroLink/Wabisabi

All outputs are equal (or tiered by denomination). Best privacy.

Variable-output PayJoin (BIP78)

Different mechanism — see payjoin/SKILL.md.

Use cases

Privacy-conscious users wanting on-chain anonymity.
Pre-emptive privacy before storing or spending large amounts.
Pre-spend mixing for high-profile addresses.

Costs

Per-round fee to coordinator: small percentage of input.
On-chain tx fee: shared among participants.
Time: multiple rounds for full anonymity (hours typical).

Status (September 2026)

Wasabi Wallet 2.x: operational. zkSNACKs discontinued the default coordinator on 1 June 2024; the same-day v2.0.8 release added coordinator selection in the GUI and moved the repo from the zkSNACKs org to WalletWasabi/WalletWasabi. Stock Wasabi now ships with no default coordinator — the user pastes one in. Latest release v2.8.3 (14 Sep 2026).
Whirlpool: relaunched by Ashigaru on 23 June 2025 (new ZeroLink coordinator + Terminal v1.0.0). Tor-only; both pools reported still operating as of mid-2026. ashigaru.rs has posted nothing since June 2025, so that is the freshest operational check, not a September 2026 one.
JoinMarket: niche but operational. Reference implementation JoinMarket-Org/joinmarket-clientserver archived 27 Apr 2026 (read-only; final release v0.9.12, 21 Apr 2026), and its release notes point readers at joinmarket-ng/joinmarket-ng as the codebase under active development (0.39.2, 10 Sep 2026). NG is wire-compatible, so the maker/taker market is not split. The Jam web UI is still maintained (v2.0.0-beta.3, 24 Aug 2026).
Joinstr (Nostr-based CoinJoin coordination): experimental (status last checked late 2025).

Legal outcome (Samourai, November 2025)

The April 2024 Samourai indictment is no longer an open case. Both founders were convicted of conspiring to operate an unlicensed money transmitting business and sentenced in the SDNY:

Keonne Rodriguez (CEO): 5 years, sentenced 6 Nov 2025.
William L. Hill (CTO): 4 years, sentenced 19 Nov 2025.
Each also got 3 years supervised release and a $250,000 fine.
Forfeiture ordered: $237,832,360.55; $6,367,139.69 paid, that figure being the fees Samourai itself earned.

Design consequence: the count of conviction was unlicensed money transmission, not custody or theft. Treat "we never hold user keys" as not a defence when scoping a coordinator, and get jurisdiction-specific legal advice before operating one.

Limitations

Coordinator availability: Wasabi requires coordinator.
Anonymity set size: small rounds = weak privacy.
Post-mix hygiene required; users often re-link unintentionally.
Exchange refusals: some exchanges (esp. KYC-heavy) refuse deposits from CoinJoin outputs.

bitcoin-privacy-coinjoin