Backend Engineer - Firebase Cloud Functions, Firestore, Webhook Integration

Got it, plain text field. Here's what to paste in: We are building NAM, an AI-powered Contact Center as a Service platform for Saudi and GCC businesses. The frontend dashboard is complete. We need a backend engineer to build everything behind it across a structured three-phase engagement. What needs to be built The backend connects our AI voice platform (ElevenLabs Conversational AI) to our Firestore database and serves data to the dashboard in real time. Every inbound call a client receives is handled by an AI voice agent. When the call ends, a webhook fires with the transcript, sentiment analysis, and call metadata. The backend receives that webhook, stores the data, and serves it to the dashboard through a REST API. The system is multi-tenant. Each client is a separate business with fully isolated data. Authentication is handled via Firebase Auth with custom JWT verification on every request. Phase 1 - Build (3 months) Build and deploy the webhook receiver, Firestore schema, API layer, and auth. Deliver working production-ready backend with full documentation. Phase 2 - Iterate (3 months) Work with us through the first live client deployment. Fix issues from real usage, adjust features based on feedback, maintain stability. Phase 3 - Maintain (3 months) Maintain the system as we scale to multiple clients. 99.9% uptime is a hard requirement. Contact center operations depend on it. Stack Firebase Cloud Functions, Firestore, Firebase Auth, GCP Cloud Storage, GCP me-central2 region (Dammam, Saudi Arabia). No Twilio. No Supabase. No third-party auth services. What we are looking for Proven experience building multi-tenant SaaS backends Webhook integration experience including signature verification, idempotency, and retry handling GCP and Firebase specifically, not just general cloud experience Ability to deliver documented, handoff-ready code Direct communication and weekly check-ins throughout How to apply Send two examples of multi-tenant backends you have built, one example of a webhook integration you have implemented including any edge cases you handled, and your honest assessment of the stack above. No cover letters. A detailed technical brief is available after an initial conversation.