Systems to improve the Know Your Customer (KYC) process using blockchain technology have only been proposed at a conceptual level and they all share some attributes that make their adoption by financial institutions (FIs) very difficult. We propose and program a blockchain-based system that reduces and shares out, among the financial institutions that work with a customer, the costs of the KYC process, and also makes it possible for FIs to dynamically update the information related to the customers and for this information to be disseminated among participating FIs. Additionally, our system solves some of the attributes that hinder the adoption of previous solutions by FIs. The result is a programed, stand-alone solution that can be implemented by FIs to reduce the cost of the KYC process without requiring any central instance to store the customer’s data, and in which FIs share the initial costs of the KYC process, as well as the running costs of keeping the information about the customers up to date. Our system increases the level of security and regulatory compliance in the KYC process, and significantly reduces its costs for all parties involved.