Advanced Cross-Platform Flutter App Development

Cliente Freelancer · Remoto · Remoto · freelance · mid · 12.500–37.500 INR

Publicada el 2026-07-21

Descripción de la oferta

We are seeking an elite Senior Full-Stack Developer or a highly capable Development Team/Agency to take ownership of, maintain, and execute a massive expansion (Phase 3) of an established, production-grade consumer platform. The core infrastructure and initial surfaces are completely live. Phase 3 represents a major green-field extension, introducing an entire vendor/merchant ecosystem, complex new database domains, transactional/financial capabilities, and advanced security layers. The codebase is clean, well-architected, and strictly follows multi-environment development pipelines. ### Tech Stack & Current System Surfaces All surfaces share a single centralized backend API and a unified backend-as-a-service database instance. #### 1. Mobile Application (Flutter/Dart) * **Architecture & Scale:** Built with **Flutter (Dart ^3.10.0)** for iOS and Android. It consists of roughly **81 screens, 101 services**, structural models, global themes, and full English/Arabic localization stacks. * **Design Pattern:** Utilizes a highly custom, non-standard Figma design system (completely independent of standard Material UI). Services strictly follow a **three-tier pattern** (Base Data Layer \rightarrow Cached/Optimized Layer \rightarrow Offline-Capable Layer) utilizing singleton ChangeNotifier state and go_router navigation. * *Status: Live.* #### 2. Consumer Web Platform (Next.js) * **Architecture & Scale:** Built with **Next.js 15.5 (App Router, React 18, TypeScript)**, deployed on Vercel. Features full route groups matching mobile feature modules, heavy use of Server-Side Rendering (SSR) reading secure auth cookies, and deep bilingual translation (EN/AR) using next-intl with native Right-to-Left (RTL) alignment. * *Status: Live (maintaining near-total feature parity with the mobile app).* #### 3. Internal Admin Dashboard (Next.js) * **Architecture & Scale:** A separate instance built on **Next.js 16.2**. Features role-gated capabilities resolved strictly server-side from access allowlists. Currently contains operational modules for User Management, System Notifications, Content Moderation, Server Monitoring, and Dev Ops. * *Status: Live.* #### 4. Backend REST API Gateway (NestJS) * **Architecture & Scale:** Built with **NestJS ^10 (TypeScript, Node.js >=18)** running on a dedicated Linux VPS behind an Nginx reverse proxy, managed via PM2. * **Endpoint Structure:** Features **17 distinct feature modules** and roughly **140 fully-mapped endpoints** fully annotated with OpenAPI/Swagger (~56 GET, ~57 POST, ~9 PATCH, ~8 PUT, ~13 DELETE). Handles all inbound webhooks, core throttling, global auth guards, and complex business logic. * *Status: Live.* #### 5. Database & Infrastructure Layer (PostgreSQL) * **Data Tier:** Managed **PostgreSQL** instance featuring **52 production tables** partitioned across 11 key structural domains (Auth & OTP, User Profiles, Catalogues, Wishlists/Items, Social Connections, Family/Child Profiles, Shared Contributions, Chat Systems, Gamification/XP, System Notifications, and Operation/Cron Logs). * **Security:** Every single table is strictly protected by complex **Row-Level Security (RLS)** rules. Frontend clients interface directly with the database via RLS for low-latency operations, while the NestJS backend handles privileged workflows using elevated administrative service roles. * **Realtime & Serverless:** A persistent WebSocket/Realtime pipeline drives live updates (chat, social connections, state changes). Background cron execution, transaction handling, and automated push routines run through serverless **Edge Functions**. * **Caching & Logs:** Dedicated **Redis** architecture handles backend hot-read caching. Push notifications and application crash tracking are wired into an external mobile suite. ### Integrated Ecosystem & Ecosystem Hooks * **Authentication Flow:** Phone-first approach. Primary authentication is processed via Phone OTP (SMS or WhatsApp gateways), or phone + password (where the backend securely maps the identifier underneath). Session states are strictly JWT-based. * **AI Engine & Automated Moderation:** Features automated pipeline hooks utilizing multi-model LLM text logic, multi-modal automated image/content scanners (NSFWJS + Cloud Vision integrations), and cloud-based natural language systems to automatically flag and isolate inappropriate items, text, and links before they persist in the database. * **Location Stack:** Deeply integrated map and geocoding services used for physical merchant locations. ### Scope of Work (Phase 3 Core Deliverables) The awarded vendor will be responsible for the end-to-end architecture, development, design translation, and deployment of the following blocks: #### 1. Greenfield Architecture: Merchant & Partner Web Portal * Design and build a completely brand-new, highly responsive web application from scratch using **Next.js (TypeScript)**. * Architect net-new database domains completely absent from the current platform: **Payment Processing, Wallets, Digital Gift Cards, Product Catalogues, Order Management, Merchant Accounts, Internal Advertising, and Subscription Engines**. * Build out secure vendor onboarding workflows, transaction dashboards, business analytics, and sub-merchant account management tools. #### 2. Advanced Security Layer Integration * Implement Multi-Factor Authentication (MFA) mechanics across all platforms (Consumer Web, Admin Dashboard, and the new Merchant Portal). * Integrate native Biometric Authentication (FaceID / TouchID) flows securely into the existing Flutter mobile application. #### 3. Core Scaling, Maintenance & Optimization * Expand the internal Admin Dashboard to include new sections for Marketplace Analytics, Finance/Payout Auditing, and Merchant Administration. * Audit, review, and refactor existing PostgreSQL RLS rules and NestJS Redis cache parameters to ensure rapid scaling under heavy multi-tenant transactional load. * Maintain three isolated, independent development environments (Local, Dev, Production) driven by strict reviewable/reversible SQL migration patterns.

Skills

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