I’m building a new cross-platform gaming portal and need a single, rock-solid backend that serves our Android app, browser game, and upcoming iOS release. The API must be RESTful (GraphQL as an optional layer is welcome), well-documented, and container-ready for scalable cloud deployment. Core requirements at a glance • Platforms served: Android, Web, iOS • Main modules: User authentication, game data management, and in-app purchase handling • Authentication methods to support: – Email & password – Social media login (Google, Apple, Facebook, etc.) – Two-factor authentication (OTP or push) What I expect you to deliver 1. Clean, versioned API endpoints covering sign-up / sign-in, profile, secure token refresh, game progress save-load, leaderboards, and purchase receipt validation for Google Play and the App Store. 2. Database schema (SQL or NoSQL—justify your choice) with migrations. 3. Swagger / OpenAPI docs that front-end teams can plug into immediately. 4. Automated test suite plus Postman collection for quick smoke tests. 5. Docker-based deployment scripts and a short README so I can spin up staging in one command. Acceptance criteria • Login flows work flawlessly across all three auth methods, returning JWTs or similar tokens. • Game data persists and syncs in under 200 ms round-trip on a standard US-East server. • Purchase endpoints correctly verify and log receipts from sandbox and live stores. • All endpoints covered by unit and minimal integration tests; 90 %+ line coverage. Preferred tools include Node.js/TypeScript with Express or Nest, but I’m open to Go, Django, or Laravel if you can match the performance targets. Please outline your proposed tech stack, timeline, and any past gaming or high-throughput API work when you reply.