JoinMarket

A peer-to-peer market for bitcoin coinjoins without a central coordinator, in which takers pay makers to join their transactions; its reference software was archived in April 2026 and an independent compatible version continues.

LiveCoinjoin

The reference implementation, joinmarket-clientserver, was archived on 27 April 2026 after its final release, 0.9.12; JoinMarket NG, an independent implementation whose makers and takers share the same market, was still releasing new versions, the latest 0.42.1 on 19 October 2026.

Launched: 9 Jan 2015
Token: None
Chains: Bitcoin

Checked on 23 Oct 2026. Information only, not investment advice.

How it works

JoinMarket is software for making coinjoins, single bitcoin transactions that combine coins from several people so that an observer cannot tell whose output is whose, without a central coordinator. Chris Belcher announced it on 9 January 2015, and Bitcoin Optech describes it as the first implementation of a coinjoin protocol that was not broken. Its answer to the problem of finding others to join is a market: makers keep coins available for coinjoins and earn a fee, set either as a percentage of the amount or as a fixed number of satoshis, while takers can create a coinjoin at any time and pay those fees, along with most of the network fee. Each user runs the software with their own Bitcoin Core node, which can be pruned, and private keys never leave the user's computer.

A taker reads the orderbook of makers' offers, chooses makers and negotiates the transaction with them; each participant adds inputs and receives an output of the same amount, the coinjoin amount, and any leftover value goes to a separate change output. To stop takers from asking makers for their coin details over and over, a practice called snooping, a taker must present a commitment that can be used only once. To make it costlier to flood the market with fake makers, a sybil attack, version 0.9.0 of 31 July 2021 added fidelity bonds: makers can lock coins in timelocked outputs, and takers use these bonds when choosing whom to join.

The bots first talked through IRC servers. Since version 0.9.6 of 8 May 2022 they can instead serve and connect to Tor onion services: a taker contacts directory nodes first and then makers directly, so most of the negotiation happens peer to peer rather than through a central server, and messages are end-to-end encrypted either way; Tor has been required since that version. Public orderbook watchers show the market's offers, but most run as onion services, and the clearnet mirror that the README lists returned an error when checked on 16 October 2026.

A JoinMarket wallet is split into mixing depths, each treated as a different identity: coins from different depths are never combined in one transaction, and a change output stays in its depth, because merging it later with a coinjoin output would make the coinjoin easy to undo. The documentation says a single coinjoin does not give a significant privacy boost and points users to the tumbler, a script that runs a series of coinjoins. JoinMarket is used from the command line, a desktop interface or third-party front ends such as the Jam web interface. The reference implementation, joinmarket-clientserver, published its final release, 0.9.12, on 21 April 2026 and was archived on 27 April 2026. JoinMarket NG, an independent implementation in Python under the MIT licence that can also run on a light Neutrino backend, is wire-compatible with it: makers and takers from both share one market. Its latest release when this profile was checked was 0.42.1, of 19 October 2026.

Coinjoin volume over time

No daily history for JoinMarket is held on this site. JoinMarket holds no deposits, so it has no TVL, and no free public source of daily figures for the number or value of its coinjoins was found when this profile was checked on 23 Oct 2026. What public data can show is set out on its card in the Bitcoin privacy section of Protocols.

What it hides and what it does not

What it hides

Which of the equal outputs of a coinjoin belongs to which participant: the taker and every maker receive the same amount.
The participants' network addresses, as bots talk over Tor onion services, and the content of their messages, which is end-to-end encrypted.

What it does not hide

That a transaction is a coinjoin, and every coin that went into it, on chain.
The change outputs, which are not mixed: merging one later with a coinjoin output can make the coinjoin easy to undo.
Much, after a single coinjoin: the documentation says one coinjoin does not give a significant privacy boost and recommends a series of them through the tumbler.
Makers' coins to takers who abuse the commitment check: a flaw fixed in April 2026 let an attacker gather information on many of makers' coins.

Drawn from how it works, above; the sources are listed at the end of the page. Where privacy still leaks explains the patterns, such as timing and amounts, that can give users of any design away.

Audits

None found when this profile was checked on 23 Oct 2026.

Incidents

Three incidents, oldest first: flaws, exploits, sanctions, prosecutions and other events that affected the project or its users.

20 Oct 2021

Version 0.9.3 fixed a bug through which makers using the relfee option could lose up to their transaction fee contribution in a coinjoin, and the maintainers said all earlier releases should be treated as deprecated for makers.

Source: v0.9.3: Urgent bugfix upgrade for makers, and JSON RPC API GitHub, JoinMarket-Org, 20 Oct 2021
21 Apr 2026

The final release, 0.9.12, fixed what its notes call a denial-of-service vector: commitments that should be usable only once were not checked in the right format, so they could be reused almost continuously, and an attacker doing so aggressively could retrieve information on many of makers' coins over a long period, 'exactly the attack that the taker commitments were supposed to thwart'. The flaw was reported by m0wer; the notes do not say when it was introduced.

Sources: Release notes for 0.9.12 GitHub, JoinMarket-Org, 21 Apr 2026; v0.9.12: Final release of joinmarket-clientserver GitHub, JoinMarket-Org, 21 Apr 2026
27 Apr 2026

The reference implementation was archived, with its code and releases left in place but no further updates. The final release notes say it had not been under active development for a considerable time, warn users not to keep using the code without independent confidence that it is not exploitable, and point to JoinMarket NG as an alternative under active development, while saying this is not a recommendation and that use of this or any similar software is the user's own responsibility.

Sources: v0.9.12: Final release of joinmarket-clientserver GitHub, JoinMarket-Org, 21 Apr 2026; Release notes for 0.9.12 GitHub, JoinMarket-Org, 21 Apr 2026; joinmarket-clientserver repository (archive notice) GitHub, JoinMarket-Org, 27 Apr 2026

Milestones

Seven milestones, oldest first.

9 Jan 2015
Chris Belcher announced JoinMarket, a market of makers, who earn a fee for providing liquidity, and takers, who pay for coinjoins.
Source: Coinjoin (topic page) Bitcoin Optech
Jul 2019
Chris Belcher proposed fidelity bonds on the Bitcoin-Dev mailing list to answer a known sybil problem, in which one attacker running enough maker identities could be picked in nearly every coinjoin: makers would create a lasting identity by burning or timelocking bitcoin, and takers would choose makers weighted by the size of that sacrifice, making such attacks costlier though coinjoins likely dearer.
Source: Bitcoin Optech Newsletter of 31 July 2019 (fidelity bonds for improved sybil resistance in distributed coinjoin) Bitcoin Optech, 31 Jul 2019
31 Jul 2021
Version 0.9.0 introduced fidelity bonds: makers can create timelocked outputs as bonds, and takers use them as information when choosing makers, for protection against sybil attacks.
Sources: joinmarket-clientserver v0.9.0 release GitHub, JoinMarket-Org, 31 Jul 2021; Bitcoin Optech Newsletter (JoinMarket 0.9.0 released with implementation of fidelity bonds for coinjoin sybil resistance) Bitcoin Optech, 11 Aug 2021
8 May 2022
Version 0.9.6 introduced onion message channels, through which bots serve and connect to Tor onion services and negotiate mostly peer to peer, and made Tor a requirement.
Sources: v0.9.6: New quasi-p2p onion-based messaging and fidelity bond change GitHub, JoinMarket-Org, 8 May 2022; How to set up onion message channels in Joinmarket GitHub, JoinMarket-Org
21 Apr 2026
joinmarket-clientserver published its final release, 0.9.12, which also raised the minimum Bitcoin Core version from 0.18 to 29.0 and moved to descriptor wallets, needed for Bitcoin Core 30.0 and later.
Source: Release notes for 0.9.12 GitHub, JoinMarket-Org, 21 Apr 2026
19 Jun 2026
Bitcoin Optech reported the release of JoinMarket NG 0.32.0, a version of the independent implementation that shares the JoinMarket market.
Sources: Bitcoin Optech Newsletter (JoinMarket NG 0.32.0 released) Bitcoin Optech, 19 Jun 2026; joinmarket-ng README GitHub, joinmarket-ng
19 Oct 2026
JoinMarket NG released versions 0.42.0 and 0.42.1, the latest when this profile was checked, after 0.41.0 on 13 October 2026.
Sources: joinmarket-ng releases (API listing) GitHub, joinmarket-ng, 23 Oct 2026; joinmarket-ng release 0.41.0 GitHub, joinmarket-ng, 13 Oct 2026

Funding

Two sources of funding, oldest first. Amounts are in US dollars; a dash means the sources give no US dollar figure.

Date	Round	Amount	Investors
31 Mar 2026	OpenSats grant to JoinMarket NG, one of three first-time grants from its General Fund in the seventeenth wave of bitcoin grants; no amount was stated Source: Seventeenth Wave of Bitcoin Grants OpenSats, 31 Mar 2026	–	OpenSats
1 Apr 2026	HRF Bitcoin Development Fund grant to JoinMarket-NG, to support development and the external security audits needed to launch it fully, in a round of 1.5 billion satoshis for 26 projects; no amount was stated for JoinMarket-NG Source: HRF's Bitcoin Development Fund announces support for 26 projects worldwide Human Rights Foundation, 1 Apr 2026	–	Human Rights Foundation, Bitcoin Development Fund

Risks

The reference software is archived, and its maintainers warn against running it without independent confidence that it is not exploitable; JoinMarket NG is a newer codebase, and no published security audit of either was found: its README thanks @1440000bytes (Floppy) for an ongoing external audit, and the HRF grant of April 2026 is meant to pay for the audits it needs to launch fully. Makers keep a wallet online with Bitcoin Core to stay available, so bugs can cost them: in 2021 a fee bug could take part of a maker's fee contribution, and the flaw fixed in April 2026 let an attacker gather information on makers' coins. Fidelity bonds raise the cost of posing as many makers but do not rule it out. Privacy depends on how many makers are active and on how coins are spent afterwards: no free public figures for the market's size could be read from the clearnet when this profile was checked, single coinjoins give little privacy, and merging change with mixed coins can undo a mix. There is no company or coordinator to shut down, but the final release notes say use of this or any similar software is the user's own responsibility, and rules on mixing differ from country to country.