The group’s concept is simple. People sign up online and get access to a database that is kind of like a members-only Craigslist. One unit of TEM is equal in value to one euro, and it can be used to exchange good and services. Members start their accounts with zero, and they accrue credit by offering goods and services. They can borrow up to 300 TEMs, but they are expected to repay the loan within a fixed period of time.

Members also receive books of vouchers of the alternative currency itself, which look like gift certificates and are printed with a special seal that makes it difficult to counterfeit. Those vouchers can be used like checks. Several businesspeople in Volos, including a veterinarian, an optician and a seamstress, accept the alternative currency in exchange for a discount on the price in euros.

A recent glimpse of the database revealed people offering guitar and English lessons, bookkeeping services, computer technical support, discounts at hairdressers and the use of their yards for parties. There is a system of ratings so that people can describe their experiences, in order to keep transparent quality control.

(The network uses open-source software and is hosted on a Dutch server, cyclos.org, which offers low hosting fees.)

The group also holds a monthly open-air market that is like a cross between a garage sale and a farmers’ market, where Mr. Mavridis used his TEM credit to buy the milk, eggs and jam. Those goods came from local farmers who are also involved in the project.

“We’re still at the beginning,” said Mr. Mavridis, who lost his job as an electrician at a factory last year. In the coming months, the group hopes to have a borrowed office space where people without computers can join the network more easily, he said.