I’m building a B2B SaaS platform in the e-commerce operations space that will operate as a fully independent application, with Shopify used strictly as an integration layer for authentication and data syncing. The core product will not be a Shopify-first app — it will be a standalone, multi-tenant SaaS platform designed to scale beyond a single ecosystem. Shopify will function primarily as a connection point via OAuth and webhooks, while the primary logic, automation engine, and dashboard experience will live in the external platform. The system will ingest order and fulfillment data, process it through a background monitoring engine, and trigger automated workflows based on defined conditions. This requires strong backend architecture, event handling, webhook management, queue systems, and subscription billing integration. The platform must be built with scalability in mind from day one, including a clean API-first structure that allows expansion into additional e-commerce platforms in the future. I’m looking for a senior-level full-stack developer with experience building multi-tenant SaaS products, background job processing systems, webhook-driven architectures, and usage-based subscription billing. This is not a simple Shopify embedded UI project — it is a true SaaS build with a lightweight integration app serving as the connection layer. The focus is long-term scalability, clean architecture, and strong system design.