Senior Full Stack Enterprise Integrations Amazon SP-API, Shopify, Cin7, HubSpot, QuickBooks, AI SaaS

We are looking for an experienced Full Stack Engineer with deep expertise in enterprise e-commerce integrations, API development, and business automation. This role focuses on building scalable integrations between e-commerce platforms, CRMs, ERPs, accounting systems, and AI-powered applications. The ideal candidate has extensive experience designing secure, production-ready backend systems and developing modern SaaS products. Responsibilities * Develop and maintain Amazon SP-API integrations (Orders, Listings, Inventory, FBA/FBM, Feeds, Reports) * Build advanced Shopify integrations using GraphQL and REST Admin APIs * Create real-time inventory synchronization with Cin7 Core and Cin7 Omni * Integrate QuickBooks Online and Xero with e-commerce platforms * Connect HubSpot, GoHighLevel (GHL), Salesforce, and custom CRM systems * Design secure REST APIs, GraphQL APIs, OAuth 2.0 authentication, and webhook architectures * Develop scalable SaaS applications using React, Next.js, Node.js, TypeScript, Supabase, and PostgreSQL * Build workflow automations using n8n and AI-powered systems utilizing MCP architecture * Optimize application performance, reliability, and scalability Required Skills * Amazon SP-API * Shopify API (GraphQL & REST) * Cin7 Core / Cin7 Omni * QuickBooks Online API * Xero API * HubSpot API * GoHighLevel API * Salesforce API * Node.js / NestJS * React.js / Next.js * TypeScript / JavaScript * PostgreSQL / MySQL / Supabase * REST APIs * GraphQL * OAuth 2.0 * Webhooks * AWS * n8n * AI workflow integration (MCP, OpenClaw, Claude Code, Lovable) Preferred Experience * Multi-channel e-commerce platforms