Guide for implementing Apple App Store Connect API integrations. Use when: (1) Building API clients to manage certificates, provisioning profiles, bundle IDs, or devices, (2) Implementing JWT authentication for App Store Connect, (3) Understanding API request/response patterns and error handling, (4) Working with TestFlight builds, beta groups, or app submissions, (5) Discovering available endpoints, schemas, or capabilities via the OpenAPI spec. Includes scripts for fetching and analyzing Apple's official OpenAPI specification.