Danske Bank has transformed from a product-centric to a customer-centric organisation. In this talk, we will tell the story of core banking IT transformation, where we gradually and experimentally probed different approaches to exposing core banking information and processing assets as APIs. Through trial and error, we can now pledge to the sweet symbiosis between API enablement and customer centricity. Our talk will substantiate an API enablement model, where decentral, domain- driven APIs and events replaced centralised enterprise SOA, incrementally enabling a 360 single customer view. Domain APIs are becoming reusable Lego bricks in the enterprise API-led integration, e.g. in GDPR & PSD2 deliveries. Using standard APIs as building blocks to innovate on new customer experiences and speed up regulatory projects, we can mention success factors like DDD, MDM, customer-journey induced urgency and capability-based modelling. We will be candid about the challenges, such as API tooling and organisational ownership of aggregator and process APIs. We will dabble into the bank’s emerging reactive exploration, where customer experience apps aspire to be self-contained systems devoid of all synchronous API interactions. Consequently, core banking data and services are being “copied” at dizzying speed into satellite enclaves, raising the complexity of maintaining a strong core.