Abstract: An blockchains are secure by design and are an example of a distributed computing system and blockchain is suitable for the identity management transaction processing. In this study, we suggested a user authentication service based on blockchain. Blockchain technology enables entities independent of each other to rely on the same shared, secure and auditable source of information in a way that fits well with a system of widespread digital identity. The proposed model can be applied to various systems while guaranteeing secure authentication of users. Therefore, users can conveniently use various services without generating many accounts and passwords.