This document discusses the benefits of building APIs first before developing user interfaces. It argues that taking an "API-first" approach allows software to more easily become a platform that others can integrate with. Some key points made include: - Building APIs first is more work upfront but pays off by enabling integrations and new interfaces like mobile apps. - The process needs to break features into API endpoints before considering the user interface. - APIs should support multiple "actors" like users, integrations and bots rather than tying all data to individual user accounts. - Thinking about how features may evolve and allowing for future possibilities, like multiple related objects rather than a single one, helps future-proof APIs.