#flohmarkt is a tool to publish content in the form of a small ad / classified ad: on other fediverse services it scrolls by in the timeline. On a flohmarkt site it sticks in its place like a slip of paper containing a note on some bulletin board.
People can offer or search for services or goods. The federation radius irl across different flohmarkts can be limited by a distance setting.
Primary goal is to help people meet and exchange services, goods, opinions.
https://chrichri.ween.de/articles/dca424d/flohmarkt-a-federated-small-advertisement-server
So you only trade with people in your web of trust? That’s not feasible. People flock to these websites to trade with strangers. You don’t need a middleman to trade with people you already trust.