Q-Commerce Platform Debugging & Optimization

We are looking for an experienced developer/team to thoroughly test, analyze, and fix issues in our complete Q-Commerce multi-module platform.
Project Overview
Our platform is fully developed and includes:
Website (Frontend): Next.js
Backend: Laravel (All core features implemented)
User App: Flutter (All features integrated)
Seller App: Flutter (All features integrated)
Delivery Boy App: Flutter (All features integrated)
The system is multi-module & multi-zone based, and all major features are already built.
Now we need deep testing + issue fixing + optimization.
Scope of Work (Very Important)
You will need to audit, test, and fix the entire system:
1. Backend (Laravel)
All APIs testing (User, Seller, Delivery, Admin)
Authentication & authorization flow
Order lifecycle (create → assign → deliver → complete)
Payment integration & wallet system
Zone-wise logic working properly or not
Database optimization & bug fixing
Admin panel full workflow testing
2. User App (Flutter)
Login/Signup (OTP, Truecaller, etc.)
Product browsing, cart, checkout
Order placement & tracking
Payment flow (COD / Online)
Notifications & real-time updates
UI/UX bugs and crashes
3. Seller App (Flutter)
Product add/edit/delete
Inventory & stock management
Order accept/reject/processing
Earnings & reports
Seller dashboard functionality
4. Delivery Boy App (Flutter)
Order assignment & acceptance
Navigation & pickup/drop flow
Earnings & incentives
Online/offline status
Order completion logic
App performance & alerts
5. Website (Next.js)
UI responsiveness
Product listing & search
Cart & checkout
API integration with backend
SEO & performance optimization
Multi-Module & Zone Testing
Multiple zones working correctly or not
Order flow across zones
Seller & delivery mapping per zone
Distance / proximity logic
Config-based features (if any)
Key Responsibilities
Identify all bugs, issues, and broken flows
Fix backend + frontend + apps issues
Ensure smooth integration across all modules
Optimize performance (API, app speed, DB queries)
Deliver a fully working, production-ready system
Expected Outcome
All modules working perfectly
No major bugs or crashes
Smooth order flow end-to-end
Clean, optimized, and stable system
Who Should Apply
Experience in Laravel + Flutter + Next.js
Strong debugging & system understanding
Experience with multi-vendor / delivery / q-commerce apps preferred
This is not a basic task — we need complete system-level testing & fixing.
Only apply if you can handle end-to-end responsibility.
Apply with:
Previous similar work
Your approach for testing & fixing
Estimated timeline & cost