I have already prototyped the front-end of my SaaS product in AIStudio and now need a production-ready backend that plugs in cleanly. Here is what I am after: • Core services: full user management (registration, profile, roles), payment processing for subscriptions and one-off charges, plus an analytics & reporting layer so I can surface usage metrics to both admins and end-users. • Data layer: a solid SQL database—please design the schema, create all migration scripts, and keep performance in mind for future scale. • Security: OAuth is my preferred path for authentication and authorization. I’ll need the standard flows (sign-in, refresh, revocation) exposed through the API. • API: clean REST (or GraphQL if you can justify the benefit) endpoints documented with Swagger/OpenAPI so my AIStudio front-end can consume them effortlessly. • Payment gateway integration: connect to a mainstream provider and return webhooks I can act on. • Analytics: aggregate key events and expose concise reporting endpoints; bonus points if you suggest lightweight dashboards or pre-calculated views. Deliverables 1. Source code in a public-cloud friendly framework (Node.js, Python, Go—your call, as long as it is well-structured and tested). 2. Database schema and migrations. 3. Postman (or similar) collection demonstrating every endpoint. 4. Deployment guide covering environment variables, secrets handling, and CI/CD hooks. 5. Short hand-off call or video walkthrough so I can hit the ground running. Acceptance criteria • All endpoints authenticated via OAuth. • Payments flow end-to-end in sandbox mode. • At least three actionable analytics metrics exposed. • Unit tests with 80 %+ coverage. If this sounds like an engaging build and you have proven backend chops, I’d love to see how you’d approach it and an outline of the stack you recommend.