Car Marketplace & Live Auctions

I need a modern web platform where owners can list used cars and buyers can bid in real-time auctions. Users will sign up as either buyers or sellers, manage their own listings with multiple photos, and compete through a live bidding module that shows the current high bid and a countdown timer.

Search must let visitors narrow results by Brand and Location; price filtering can wait until a later phase. Users should be able to set alerts (only set alerts, no need to save entire searches) and receive both Email notifications and In-app notifications when a watched auction changes status or a new car matching an alert appears.

A lightweight admin panel is required for user, listing, and auction oversight. The whole interface has to be fully responsive and feel as smooth on mobile as on desktop.

Preferred stack: React or Next.js for the front end, Node.js with MongoDB on the back end, and Socket.io (or an equivalent real-time layer) to power the auctions. If you think another approach will perform better, let me know why.

Please share:
• A brief portfolio or live links to similar marketplace or real-time apps you have delivered
• Your suggested tech stack (if different)
• Estimated cost and a 1–2 week timeline, broken down by milestones if possible

I will review proposals as they arrive and move quickly once I see the right fit.