The document discusses adopting a contract-first approach to API development where the API contract is defined using OpenAPI before any code is written, which allows different teams to work in parallel without risk of integration issues, and tools can generate code stubs and tests from the contract to speed up development. It recommends designing the UI first through prototyping and user research to drive the API design, using a mock server during UI development for rapid iteration, and generating and validating the server implementation from the OpenAPI contract.