A synthetic Central Bank Digital Currency (sCBDC) is a privately issued payment instrument fully backed by central bank liabilities. GNU Taler is a token-based digital payment system that offers a range of unique features to its users, pairing ease-of-use with payment privacy and informational self-determination. As it is Free Software, any retail bank can easily adopt the technology to create an sCBDC, benefiting from its unique features and low operational costs, while receiving risk-free interest rates from central bank reserves. Our work introduces the concept and contrasts it with related payment instruments.