Full-Stack Developer — Internal AI Web App (Claude API + Database + Auth)

We are building an internal AI-powered nutrition coaching tool called NATE (Nutrition and Training Expert) for our team of 3-5 staff members. We already have a fully functional HTML/JavaScript chat interface built that calls the Anthropic Claude API. The tool works — we just need it properly hosted with a backend, database, and staff login. WHAT WE NEED BUILT: 1. Backend proxy server (Node.js or Python/FastAPI) — Route API calls from the browser to Anthropic securely — Store the Anthropic API key as a server-side environment variable — This solves our current CORS issue and keeps the key hidden 2. Staff authentication — Simple login system for 3-5 internal users (email + password) — No public sign-up — admin adds users manually — Session management so staff stays logged in 3. Database for client data — Save client profiles (form responses pasted by staff) — Save conversation history per client — Save meal plans and outputs NATE generates — Allow staff to pull up a previous client and continue where they left off — Simple search by client name 4. Ability to update the AI system prompt — Admin panel or simple config file where we can update NATE's instructions without touching the rest of the code — Updates should NOT wipe any saved client data 5. Hosting on our custom domain — We own nate.nutritionx.ai — SSL certificate — Clean deployment that is easy to update going forward WHAT WE ALREADY HAVE: — Fully built HTML/JS chat interface (we will provide the file) — Anthropic API account and API key — Domain: nate.nutritionx.ai — Netlify account (or open to other hosting suggestions) TECH STACK (flexible — use what you know best): — Frontend: existing HTML/JS (no framework needed) — Backend: Node.js + Express OR Python + FastAPI — Database: PostgreSQL, MongoDB, or SQLite — your call — Auth: simple JWT or session-based — nothing complex — Hosting: Netlify Functions, Railway, Render, Vercel, or similar THIS IS NOT A COMPLEX PROJECT. We are not building a SaaS product. This is a clean internal tool for a small team. The chat interface is already built and works perfectly — you are wrapping it in a proper backend and adding data persistence. DELIVERABLES: — Working app live at nate.nutritionx.ai — Staff can log in, use NATE, and all client data saves automatically — Admin can update the system prompt without losing data — Basic documentation so we can maintain it going forward — Clean readable code (we may want to build on this later) BUDGET: $300-800 depending on experience and approach TIMELINE: 1-5 days COMMUNICATION: Daily updates preferred. English required.