Live Proxy Bidding
Server-side proxy bid engine with anti-sniping extensions and bid history streaming.
Marketplace
Numismatic Auction Platform
Where serious collectors compete for history. A live auction platform for rare coins built like a financial exchange — with KYC, anti-sniping, and a back-office that scales to seven figures in monthly bids.
100+
API route handlers
50+
DB query modules
9
User roles supported
0
Failing tests on main
Screenshots
Overview
A complete digital auction house, built ground-up for numismatic collectors. Sellers consign rare coins, buyers compete in live bidding battles, and the platform handles every messy step in between — identity verification, money flows, settlement, disputes — without ever calling a human.
The Challenge
Until now, rare coin collectors in Bangladesh had two bad options: trust strangers in WhatsApp groups, or fly to overseas auction houses. There was no platform that could prove a coin's provenance, hold money safely until delivery, and catch the last-second 'snipers' who steal auctions in the final five seconds. Build trust at scale or watch the entire market move offshore.
The Solution
I designed the system like a stock exchange — every bid is recorded, every action is audited, every user is verified. A server-side bidding engine eliminates sniping with automatic time extensions. KYC document review, risk scoring, two-person approval for destructive actions, and full GDPR compliance ship together as one integrated back-office. Stress-tested with 1,000+ concurrent simulated bidders before launch.
Tech Stack
Frontend
Next.js 15 App RouterReact 19Tailwind CSS
Backend
Next.js Route HandlersServer ActionsServer-Sent Events (SSE)
Database
PostgreSQLDrizzle ORMDrizzle migrations
Testing
Vitest unit testsPlaywright E2EStress-bid simulator
Infra
Docker ComposeCron job runner
Auth & Compliance
JWT sessionsRate limitingTOTP 2FAKYC review queueFull audit log
Key Features
Consignment Workflow
Multi-step state machine: submit → review → accept → list → auction → settle.
KYC & Risk
Document upload + admin review queue with risk scoring and blacklist controls.
Invoicing & Settlements
Auto-generated buyer invoices and seller settlements with deductions and payment tracking.
Admin Console
Approvals, user management with impersonation, audit log viewer, KPI dashboards.
Watchlist & Notifications
Per-user lot watchlist with real-time outbid notifications via SSE.
My Role
Full-Stack Architect & Lead Developer
Sole engineer — owned PRD, schema design, bidding engine, KYC/admin workflows, settlement logic, and the entire E2E test suite.
Results & Impact
- Production-ready auction back-office with full audit compliance
- Bidding engine validated against stress simulator with 1000+ concurrent bids
- End-to-end Playwright coverage for catalog browse, bidding, and account flows
- Live SSE notifications keep bidders updated without polling