Full-stack developer to build an AI-powered web app from a finished prototype + spec

Hi. I’m a non-technical founder. I’ve already built working React prototypes for an emotional-intelligence self-assessment web app using AI tools, and I have a complete written spec / developer handoff document. I’m looking for a full-stack web developer to take it from prototype to a live, paid product. This is a WEB APP (not mobile). HOW I WANT TO WORK: Fixed price, broken into milestones. I’ll review and approve each milestone before releasing payment and moving to the next. Please quote a fixed price per milestone (not hourly), with a timeline for each. WHAT’S ALREADY DONE (I’ll provide): • Working React prototypes of the full user flow • Scoring and results/interpretation logic • A complete developer handoff brief with the spec So you’re building from a clear, finished brief — not guessing at requirements. SCOPE / MILESTONES: 1. Core assessment + report Productionise the existing React prototype, consolidate the scoring + interpretation logic into one shared module (currently split across two files — flagged in the handoff doc), generate the results report, deploy to live hosting. 2. Accounts + saved progress Backend, database, user sign-up / login (auth), so users can save and return to their results. 3. Payments + premium tier Integrate Stripe or Paddle including webhooks, and gate the free vs premium experience. 4. AI coach + premium content An AI chat ‘coach’ feature and a premium plan, built on the Anthropic or OpenAI API. WHAT I’M LOOKING FOR: A developer comfortable across front-end and back-end who has shipped live web apps with auth and payments. Please share 1–2 relevant projects you’ve taken to production, your fixed price per milestone, and your timeline. Happy to start with milestone 1 and continue with the same person through the rest if it goes well. Thanks.