Real-Time Sneaker Marketplace Build -- 2

I’m bringing to life India’s first real-time marketplace dedicated to limited-edition sneakers and other coveted collectibles. The vision is a transparent bid/ask environment backed by iron-clad authenticity checks, and I want you to architect and deliver the entire stack.

Core requirement
The heart of the platform is a live bidding engine that updates instantly for every user. Latency has to feel negligible, whether someone is on the web interface or inside the mobile app.

Multiplatform reach
A seamless experience on both a modern web platform and companion iOS/Android apps is non-negotiable. I expect a shared codebase where it makes sense, yet each surface must feel native and fast.

What I need from you
• System architecture for the real-time bid/ask flow (web sockets, push, or any proven low-latency tech you’re comfortable with)
• Responsive web application built with a contemporary framework
• Native-feel mobile apps (React Native, Flutter, or your preferred cross-platform tool) delivered to the respective stores
• Admin console for listing management, dispute handling, and manual authentication overrides
• Secure user onboarding with profiles, KYC flow, and transaction history
• Plug-and-play module for authenticity verification so we can later connect in-house or third-party experts without refactoring core code
• Payment gateway integration suitable for Indian and international buyers
• Deployment pipeline, basic observability, and clear documentation to keep the platform maintainable after hand-over

Acceptance criteria
1. Any new bid is propagated to all active sessions in ≤300 ms on a 4G connection.
2. The same user can place, modify, or cancel bids interchangeably from web and mobile without state drift.
3. Listings cannot move to “Sold” unless the authenticity module returns a positive check.
4. End-to-end demo on staging showing a full transaction from listing creation to order completion and settlement.

Bring your stack recommendations, a timeline with sensible milestones, and examples of similar real-time work you’ve shipped. I’m ready to start immediately and iterate closely with you until the first pair of sneakers changes hands through our platform.