I’m building a multi-tenant B2B Fintech platform made up of three interconnected web portals—Admin, Merchant, and Retailer—all running on a unified Node.js stack. Each portal serves a distinct role in our payments ecosystem, so the codebase needs to be modular yet shareable, with strong API contracts and airtight security. Admin Portal The back-office tool must let me create, suspend, and permission users, view real-time analytics, and control every step of the payment flow. Direct hooks into both internal and third-party APIs are mandatory so business teams can plug in new data sources without a rebuild. Merchant Portal Merchants will manage catalog data, view settlement status, and download on-demand reports. A clean dashboard that mirrors the Admin’s analytics—filtered to the merchant’s own data—is expected, and all actions must cascade to the payments engine instantly. Retailer Portal Retailers need a fast, responsive interface to browse products, place orders, and track payment confirmations. The UX here should feel consumer-grade even though it rides on the same B2B backbone. Core expectations • Single-sign-on and role-based access control across all portals • RESTful (or GraphQL if justified) services built in Node.js with clear Swagger / OpenAPI docs • Reusable React (or similar) front-end components, fully responsive • CI/CD pipeline scripts so I can deploy to AWS or a comparable cloud in one command • Automated tests that cover critical payment logic When the build is complete I should be able to spin up the stack, invite a merchant and a retailer, run a test transaction end-to-end, and see the data light up in the Admin analytics dashboard without manual tweaks.