Senior Full-Stack Engineer — Multi-Tenant SaaS Architecture

We're hiring a Senior Full-Stack Engineer to build a multi-tenant SaaS platform for local service businesses. Engagement starts with a paid assessment phase — 20–30 hours, capped at 10–15 hrs/week, 2–4 weeks — reviewing our existing codebase and confirming or revising the build plan before any full build work is authorized. Phase 2 (the full build) begins only after that assessment is reviewed and accepted, and is not guaranteed to the same contractor. We need someone who has personally architected a multi-tenant system before — not worked inside one someone else designed.

Responsibilities

• Review existing prototype and codebase; deliver a written evaluation of architecture, risks, and gaps (Phase 1)
• Architect and build the multi-tenant SaaS platform in Node.js and TypeScript
• Implement PostgreSQL with row-level security as the tenant-isolation mechanism
• Deploy via serverless functions on Vercel or Netlify — the existing backend is already built serverless-first
• Build and secure webhook infrastructure — signature verification, idempotent event processing
• Work through documented pull requests, with automated tests and staging verification before production
• Provide two written progress updates per week, minimum, plus at least one call per week

Required Skills

• Personally architected a multi-tenant system, with specific evidence you can show — this is the single most important requirement
• Node.js and TypeScript
• PostgreSQL, specifically with row-level security implementation
• Serverless deployment (Vercel or Netlify)
• Webhook integration and signature verification
• Comfortable working within a defined assessment-then-build structure, not open-ended scope

Nice to Have

• Voice AI / conversational AI integration experience (Retell, Bland, Vapi, or similar)
• Frontend framework familiarity