Legacy/Classic v0.3.80 Namecoin. Namecoin is a decentralized key/value registration and transfer system based on Bitcoin technology (a decentralized cryptocurrency). It can be used for multiple purposes, for example a secure and censorship resistant replacement for DNS. Ownership of a name is based on ownership of a coin, which is in turn based on public key cryptography. The namecoin network reaches consensus every few minutes as to which names have been reserved or updated.