Jam

Jam is a web interface for JoinMarket, built to make collaborative Bitcoin transactions approachable. JoinMarket is capable software that has historically been driven from a terminal and configuration files; Jam wraps it in something you can click through.

The problem it addresses is that Bitcoin's ledger is public. Anyone can follow coins from address to address and assemble a picture of what you hold and where it came from. A collaborative transaction, or CoinJoin, combines several people's inputs and outputs into a single transaction so an outside observer cannot tell which output belongs to whom.

Arranging that requires other participants with the right funds free at the right moment, which JoinMarket solves as a market rather than through a central coordinator. Takers pay a fee to have their transaction joined; makers keep funds available and collect those fees. There is no central point of failure and no operator to trust.

Jam supports both sides. Run it as a taker to improve the privacy of your own coins, or turn on maker mode and earn fees passively for keeping liquidity available — the project's own phrasing is that others will pay you just for being there. A built-in scheduler can spread a sequence of joins over time instead of doing everything at once.

It drives the JoinMarket installation on your MyNode and uses your own node throughout, so your coins and your privacy work stay on hardware you control. Jam is free, open source, and maintained by volunteers.