Full-Stack Engineer Needed to Build Core Backend for AI Voice SaaS Platform

We are looking for a senior backend / full-stack platform engineer to help us build the core backend infrastructure for TorQi, an AI voice agent platform for automotive businesses. TorQi serves auto repair shops and car dealerships with AI voice agents that answer calls, capture leads, book appointments, route calls, handle after-hours inquiries, and recover missed revenue opportunities. Current stack includes: * Retell AI for voice agents * Supabase/Postgres for data * Vercel/Next.js for dashboard * Make/n8n for some workflows * Various CRM/calendar/notification integrations We want to move production-critical workflows out of Make/n8n and into our own backend. The 90-day goal: Build the TorQi Core Backend. This backend should handle: * Retell AI webhook processing * Call logs, transcripts, recordings, and call outcomes * Lead creation * Appointment creation * CRM/calendar sync logic * Queue/background jobs with retries * Failure logging and alerts * Multi-tenant client/location/agent configuration * Admin dashboard support * QA review workflows * Usage and billing tracking What we need built: 1. Backend API A clean backend service using Node.js/TypeScript or Python/FastAPI. 2. Retell webhook receiver Retell webhooks should go to our backend first, not directly into Make/n8n. 3. Database structure Design proper Supabase/Postgres tables for clients, locations, agents, calls, leads, appointments, integrations, notifications, QA reviews, and usage records. 4. Queue/job system Set up background jobs for CRM sync, notifications, QA, appointment creation, and retries. 5. Integration framework Start with simple CRM/calendar/email/SMS/webhook integrations, but structure it so future automotive CRM/DMS integrations can be added cleanly. 6. Internal admin/debugging views Our team should be able to pull up any call, see transcript, recording, lead outcome, appointment status, webhook events, integration status, and failure reason. Required skills: * Senior backend engineering experience * Node.js/TypeScript or Python/FastAPI * Postgres/Supabase * REST APIs and webhooks * Background jobs/queues * SaaS multi-tenancy * Third-party API integrations * Error handling, retries, logging, and monitoring * Ability to work fast without over-engineering Nice to have: * Retell AI, Vapi, Twilio, or AI voice experience * LLM API/function-calling experience * Next.js/Vercel * CRM integrations * Automotive software experience Important: This is not an ML research project. We are not looking for someone to train AI models. We need a strong backend/platform engineer who can help us turn an early-stage AI voice product into a reliable SaaS platform. Please include in your proposal: 1. Relevant backend/API/integration projects you have built 2. Your recommended architecture for this project 3. Your experience with Supabase/Postgres 4. Any experience with Retell, Twilio, Vapi, or AI voice platforms 5. Your hourly rate or fixed-price estimate for the first 30-day milestone 6. Your availability