Flutter App Upgrade: Back-end, Monetisation, Cloud Sync

Title: Backend APIs, Monetisation & Cloud Sync for Flutter App (Phase 2) — Stripe/PayPal, AdMob, PDF export, Offline Sync Project type: Fixed-price or milestone-based (preferred) Platform: iOS & Android (Flutter frontend already built — Phase 1) Estimated budget: (please provide realistic fixed-price or milestone quotes) Timeline: Target 4–8 weeks (please propose realistic schedule) Project summary We’re ready to move My Penelope from MVP (Flutter app with local storage) to a production-ready Phase 2 release. Phase 2 links the existing Flutter frontend to a secure backend, introduces monetisation (one-time upgrade + ad support), adds cloud sync and PDF export, and implements robust offline-first sync and conflict handling. This job is for an experienced backend/full-stack developer or small team who can deliver secure, scalable APIs and integrate payments and ads across iOS & Android apps. Key objectives / deliverables You will deliver a production-ready backend and server-side functionality plus integration guidance for the existing Flutter app. Deliverables must include: Backend & API Design and implement database schema (users, child profiles, trackers, professionals, payment logs, sync metadata). Secure authentication + user management (JWT/Auth0 or equivalent; signup/login/password reset/token refresh). CRUD APIs for all trackers: Meltdowns, Seizures (with timed events and disturbance logs), Sleep (disturbance logs), Mood, Mobility. Tier detection and middleware for feature gating (/user/ad-status etc). Sync endpoints for cloud storage with merge logic (lastModified timestamps), retry-safe patterns, /sync/upload, /sync/fetch. Offline-first support design: store locally, queue sync, conflict resolution approach, last_synced_at metadata. PDF export endpoint: /export-pdf/:childId generating formatted PDF reports with charts (sleep/seizures/meltdowns) and grouped entries by date. Payment integration: Stripe (preferred)/PayPal one-time purchase flow + server-side create-session endpoint and webhook processing to upgrade user tier and log payments. Receipt validation + restore purchases handling. Google AdMob integration hooks / APIs for tier-based ad disabling (expose ad-status endpoint). Settings endpoints: profile deletion (hard/soft), linked professionals CRUD, restore purchase endpoint. Admin / testing endpoints or instructions for beta rollout (feature flagging). Logging, error handling and monitoring guidance (Sentry or similar recommended). Security, compliance & quality GDPR-aware data handling; secure storage of personal data. Advice on retention & consent. Implement secure coding best practice, token expiry and refresh workflow, encrypted storage for sensitive fields. Unit / integration tests for key API endpoints and documented test cases. Documentation & handover API docs (OpenAPI/Swagger), deployment instructions, database schema docs. Admin testing instructions and beta rollout checklist. Code delivered to our repo; full ownership/rights transferred. Optional: short training session (video / call) for founders on how to use admin/testing flows. Tech preferences & constraints Frontend: Flutter (already built) — you will integrate with the existing screens. Backend: your choice (Node.js/Express, NestJS, Python/FastAPI, Go, or Supabase functions). Supabase can be used for DB and auth if proposed — but ensure offline sync and PDF export requirements are satisfied. DB: Postgres (preferred), or other relational DBs. Cloud storage for files (images/videos in future) – S3-compatible recommended. PDF generation libraries (server-side) that support charts (e.g., wkhtmltopdf, Puppeteer, ReportLab, or server-side chart rendering). Payment: Stripe preferred (server-side session + webhook). PayPal option acceptable if included. Ads: Google AdMob integration hooks (mobile SDK handled in-app; provide server-side ad-status endpoint). Acceptance criteria All APIs implemented and documented; passes security checks; unit/integration tests exist for key flows. Payments working end-to-end (create-session, webhook, tier upgrade, restore purchase). Cloud sync works: upload/fetch, merge logic, robust retry and offline behaviour validated in beta. PDF export produces well-formatted export with charts and entries grouped by date. Ad-status endpoint reliably controls ad visibility based on user tier. Smooth integration instructions for Flutter dev to hook frontend to backend endpoints. Beta release build (iOS & Android) prepared with instructions and admin test cases. Required experience & skills Strong backend/API experience (5+ years preferred) and prior delivery of mobile app backends. Experience with payment integrations (Stripe + webhook processing) and receipt validation. Experience with offline-first sync patterns, merge logic and conflict resolution. Experience with PDF generation and charting on server-side. Familiarity with Google AdMob integration patterns and tier-based gating. Security & GDPR best practice applied to user data. Clear English communication, thorough documentation, and Git-based workflow. Examples of previous work: links to similar projects in healthcare, education, or apps handling sensitive data preferred. Nice-to-have Experience with Supabase/Firebase. Experience with medical or SEND / education apps, or data-sensitive apps. Experience building admin dashboards or clinician/education portals. Availability for short UX support sessions to help integrate backend with frontend. Proposal requirements Please include in your bid: Short cover note describing your approach and whether you recommend Supabase or a custom backend (and why). High-level implementation plan split into milestones (e.g., Auth & DB → Payments & Tiering → Sync & Offline → PDF Export & Settings → QA & Beta). Cost estimate (fixed price or milestone breakdown) and realistic timeline (weeks/dates). Sample of relevant previous work (GitHub, App Store/Play links, case studies). Names / CVs of team members who will work on the project. Availability to start. Any assumptions or risks you see and how you’d mitigate them. Legal/administrative We require a short NDA before sharing production details. Full code ownership and IP transfer upon completion & final payment. Regular milestone payments tied to acceptance criteria. If this matches your skills and availability, please respond with your proposal and we’ll review and schedule short interviews with shortlisted candidates. Thank you — we’re excited to find the right partner to take My Penelope to Phase 2.

Project ID: 39720551