I’m building a subscription-based service that lets customers reserve time slots through a mobile app and a companion website. The project covers three platforms from day one—iOS, Android and a fully responsive web interface—so a shared codebase or closely aligned stacks will keep maintenance sensible. Core functionality is already defined: users create and manage their own accounts, choose a plan, pay securely, and see an always-up-to-date booking calendar before confirming their reservation. Recurring payments, free-trial logic and prorated upgrades or downgrades all have to flow smoothly through the same checkout. Beyond that I’m flexible about the underlying tech; what matters is a clean, well-documented architecture that can scale as the subscriber base grows. API design, database schema, admin dashboards and deployment pipelines should all be handled inside the engagement. By hand-off I expect: • Production-ready iOS and Android builds accepted in their respective stores • A responsive web app deployed to my hosting account or cloud service of choice • Source code in a private repo with clear README, environment samples and seed data • A succinct setup guide and a recorded walkthrough of the admin/ops panel to speed up future onboarding Unit tests around critical flows (authentication, payments, booking logic) will be part of the definition of done. Let me know which frameworks, payment gateways and CI/CD tools you recommend and how you would phase the milestones so we can start planning the release schedule right away.