Boozt, a prominent online retailer in the Nordics, chose to shift from a third-party payment gateway to its own payment processing service, Kronor. To achieve this, they formed an independent team with full autonomy. This team, under the leadership of José Lorenzo, the Director of Engineering, made an architectural decision to concentrate the majority of the payment gateway's application logic within the database. This approach was driven by the transactional nature of payment processes and the team's prior experience. José Lorenzo will discuss this choice, the use of statecharts for application logic, ensuring system observability, and successful scalability during events like Black Friday.