Senior Full Stack SaaS Architect & Developer (WhatsApp-Based Business Operations Platform)

We are looking for an experienced Full Stack Developer who can lead the architecture, UI/UX planning, and development of a modern B2B SaaS platform. The product is a workflow and operations platform designed for service-based businesses and SMEs, with deep integrations around messaging, lead management, workflow automation, and AI-assisted operations. Requirements: • Strong experience building SaaS products from scratch • Experience with multi-tenant architecture • Strong knowledge of Node.js/NestJS, PostgreSQL, Redis and Next.js • Experience with WhatsApp Business API integrations • Experience with AI integrations (OpenAI, Claude, etc.) • Experience designing scalable backend systems • Understanding of CRM, workflow engines, automation systems, and business operations software • Ability to handle both system architecture and implementation • UI/UX understanding or ability to collaborate with a designer Project Scope: Phase 1 will focus on: • User authentication and permissions • Messaging integrations • Lead management • Workflow automation • Business dashboards • AI-assisted operational tools Deliverables: • Product architecture • Database design • UI/UX wireframes • MVP development • Deployment documentation • Scalable codebase To apply: Please provide: 1. Similar SaaS platforms you've built 2. Your recommended tech stack and why 3. Experience with multi-tenant SaaS systems 4. Experience integrating WhatsApp APIs 5. Your role in previous SaaS projects (architect, developer, lead engineer, etc.) Preference will be given to developers who have built operational software, workflow systems, CRM platforms, or business automation tools.