Description We are looking for an experienced full-stack developer to build the MVP of Chromic, a medical SaaS product for dentistry, with: Web application Android app iOS app Chromic is a clinical tool, not a consumer app. Architecture, role integrity, and data reliability are far more important than flashy UI. Project overview Chromic allows dental clinics and patients to track tooth-whitening treatments over time using images and AI analysis. Core idea: Clinics provide patients with physical cards Patients register using a valid card (serial or QR) Clinic and patient are automatically linked Patients upload images during treatment Images are processed via an external AI pipeline (already available) Results are shown through clinical charts and tables Core requirements (MVP) 1. Authentication & roles (CRITICAL) Email and/or OAuth login Two roles only: Clinic Patient Role selection on first login No default role Role must be explicit, persisted, and never inferred Strict role-based routing and permissions 2. Onboarding Clinic onboarding Clinic name Contact email Country + postal code Dental notation (FDI / ADA) Clinic logo (optional) Patient onboarding Nickname only (no real names) Age ranges (not date of birth) Country + postal code Habits (brushing, staining drinks, smoking) All onboarding must be GDPR-compliant. 3. Card-based access model Clinics create cards with unique serials / QR codes Patients must enter or scan a valid card to access the app Card automatically links patient to clinic No manual patient creation Card is the gatekeeper of the system 4. Dashboards Clinic dashboard Patient list Treatment progress overview Per-patient detail view Messages / basic communication Patient dashboard Upload progress images View whitening score over time Simple, clear progress visualization 5. Image processing integration Image upload from web and mobile Trigger external webhook (Make / API already available) Receive structured analysis: Whitening score Per-tooth color (VITA scale) Store and visualize results over time 6. Platforms & architecture We expect: Web app Android app iOS app Preferred approaches (open to discussion): Web: React / Next.js or similar Mobile: React Native / Flutter / similar Backend: Node / Django / Laravel or similar Relational database preferred You may propose a different stack if you justify it clearly. 7. Visual style Clinical / medical aesthetic Black, white, greys Minimal accent colors only where informative No playful or “colorful SaaS” look What we value Clean role-based architecture Clear separation between auth, business logic, and UI Ability to think in flows and states, not just screens Experience with SaaS, health-tech, or regulated products Honest estimates and clear communication Deliverables Web app (production-ready MVP) Android app iOS app Clean, documented code Basic deployment setup Ownership of source code To apply, please include: Relevant past projects (links if possible) Proposed tech stack (web + mobile) Estimated timeline Fixed-price estimate for the MVP Any architectural concerns you foresee Existing MVP (important) An initial web-based MVP already exists, including: Core product flows Screen structure and navigation Data model and entities Image processing logic (via external webhook) This MVP is not required to be reused, but it should be used as: A functional reference A validation of product scope and flows A baseline to accelerate development and avoid rethinking solved problems The new implementation should improve structure and robustness, not reinvent the product.