Zalando built an Internal Developer Platform (IDP) to address issues with rapid growth, diverse developer needs, and inefficient team collaboration. To achieve this, they underwent a cultural transformation, creating a centralized cloud-based solution for testing and building changes, while leveraging company knowledge and research from other large companies. Team buy-in was crucial, with champions on each team helping research and build the platform. Challenges included compliance, resilience, and setting the right balance between autonomy and security. Zalando's IDP features a safety net for fast deployment without affecting others, an identity management service, and lessons learned about cultural changes and developer experience.