Project Overview We are hiring an experienced mobile app development team (minimum 2 developers) to build a modern, offline-first survey application from scratch. The app will be used by non-technical field volunteers to collect contact information and conduct surveys across campaign-based geo hierarchies, with mandatory geo-location verification and periodic server synchronization. An existing APK will be shared only for functional reference. This is not a beginner or learning project. Apply only if you have proven experience with offline-first mobile apps and GPS capture. Preferred Tech Stack Mobile App Flutter (Android first) SQLite (Drift / Floor) Riverpod (or equivalent) Flutter Intl / ARB for localization Platform Channels to reuse existing Java code for: Printing WhatsApp messaging Backend Supabase (PostgreSQL, Auth, Storage, Edge Functions) Relational schema (mandatory) DevOps GitHub (repository owned by us) GitHub Actions for CI/CD Daily APK builds If you propose an alternative stack, you must justify offline sync and relational geo-hierarchy support. User Roles and Features Super Admin Create and manage campaigns Define geo-unit hierarchy per campaign (e.g., Campaign → Mandal → Village → Booth) Upload contacts via CSV Generate passcodes mapped to geo-units One Admin passcode per geo-unit One Volunteer passcode per geo-unit Create and manage survey questions Configure app UI assets: Home screen content Splash screen image Print slip template WhatsApp campaign image Full access to Admin and Volunteer features Admin Login using geo-unit Admin passcode Team management: Assign volunteers to geo-units Enable or disable volunteers under their geo-unit Monitor data collection and survey progress Generate geo-unit–scoped reports Volunteer (Field User) Volunteers perform two distinct offline activities. Basic Contact Information Collection Collect or update: Phone number Age (if applicable) Favorability or preference Additional configurable fields Works completely offline Mandatory geo-location capture: Latitude Longitude Timestamp Accuracy (if available) Survey Execution Conduct campaign-specific surveys Works completely offline Mandatory geo-location capture at submission Auto-save survey progress Additional Volunteer Capabilities Register using geo-unit Volunteer passcode Automatically mapped to campaign and geo-unit View assigned contacts Search contacts by name, mobile number, and geo-unit Print contact slip (existing Java logic) Send WhatsApp message (existing Java logic) Participate in live polls Geo-Location and Verification (Critical) Geo-location capture is mandatory for: Basic information collection Survey submission Location must be captured from device GPS No manual location entry Works offline and syncs later Store latitude, longitude, timestamp, and accuracy Location data must be visible in admin reports Purpose: Ensure the volunteer physically visited the contact. Core Requirements Offline-First Application must function completely offline Background sync when internet is available Clear sync status indicators Server-wins conflict resolution User Experience Designed for non-technical users Minimal steps and screens Large buttons Auto-save of progress Clear offline indicators Language Support English and one Indian regional language No hardcoded strings Code and Architecture Standards (Non-Negotiable) Clean Architecture (Domain, Data, Presentation) No file exceeding 300 lines Feature-based folder structure No hardcoding SOLID principles Reusable components Centralized error handling and logging Environment-based configurations CI/CD and Delivery Expectations Daily commits to GitHub Daily APK shared for testing Branch strategy: main develop feature branches Automated build pipeline Timeline Seven-day delivery sprint. Day 1: Architecture, database schema, authentication Day 2: Campaign and geo-unit management Day 3: CSV import and offline sync Day 4: Survey engine Day 5: Admin and volunteer workflows Day 6: Reports, printing, WhatsApp integration Day 7: Testing, polish, and documentation Deliverables GitHub repository (owned by us) Production-ready APK Database schema and architecture diagram Setup and deployment documentation Knowledge transfer session Ideal Candidate or Team Minimum two developers: Flutter developer with offline-first experience Backend/PostgreSQL/sync specialist Proven experience with: Offline-first mobile applications GPS capture and synchronization Flutter with SQLite Supabase or PostgreSQL backend Comfortable with daily demos and feedback Willing to sign NDA Do Not Apply If You are a solo developer You have no offline synchronization experience You rely only on Firebase without relational modeling You cannot deliver daily builds You plan to outsource work without disclosure How to Apply Please include: Links to offline-first apps you have built Your team composition Confirmation you can deliver in seven days Your fixed price for this sprint Any risks or assumptions NDA Required