Namecoin (Namecoin) is one of the first altcoins to appear soon after Bitcoin and built on a similar technological basis. Its main idea is not merely to serve as a means of payment but to offer a decentralized system for storing key-value pairs, which allows names and domain addresses to be registered without the involvement of centralized registrars.

The project's best-known use is an alternative domain name system in the .bit zone. Users register addresses and pay for them with the network's coins, while the records are stored in a distributed ledger. This approach was conceived as a way to reduce dependence on traditional DNS and increase resistance to blocking and censorship.

Besides domains, Namecoin's technology is potentially suitable for storing other types of identification data as well. Historically the project is also important as one of the first demonstrations that a blockchain can solve tasks beyond simple money transfers.