The association ran on a lot of different systems - an AMS, conference tools, learning management, third-party integrations. None of them talked to each other in a clean way. So I designed and co-developed several abstraction layers that sat between our websites and all those back-end systems.
The key idea: as long as we maintained the abstracted interfaces, the organization could swap out any vendor - conference registration, LMS, whatever - without affecting a single website. Everything continued to work as if nothing changed. That decoupling gave us real flexibility when evaluating and switching vendors over the years.