Custom Web & Mobile App

Ebidzy: Real-Time Reverse Auction Platform

Real-time price-drop engines and concurrency-safe order execution across cross-platform channels.

Client:Startup Auction Portal
Timeline:6 months
Team:Lead Systems Architect
NestJSNext.jsReact NativeRedisPostgreSQLWebSocketsStripe
System Architecture

The Challenge

Resolving severe network clock drift in client-side countdowns and preventing race conditions and double-selling when thousands of users simultaneously trigger Buy Now clicks.

The Solution

Engineered an NTP-style latency handshake syncing all client clocks to absolute server time and formulated a 3-layer concurrency-safe ordering pipeline.

My Approach

1

State Isolation

Separated high-frequency bidding telemetry entirely into memory caches (Redis HASH) to shield primary database from excessive SQL write-locks.

2

NTP Clock Handshake

Constructed a WebSocket-based handshake estimating ping latency and adjusting client device timers to synchronize with server clock.

Results & Impact

<5ms
Distributed Lock Time

Redis Redlock overhead during simultaneous Buy clicks

15K req/s
Concurrency Throughput

Zero deadlock transaction validation capacity

Technical Highlights

3-Layer Transaction Lock

Utilizing Redis Redlock to serialize, followed by PostgreSQL row-level locks for transaction write-back.

SELECT status, winner_id FROM auctions WHERE id = $1 FOR UPDATE;

Lessons Learned

  • In-memory caches are critical for real-time states
  • NTP handshakes are required for timing equity

Next Steps

  • Integrate localized multi-currency payout wallets via Stripe Connect
  • Deploy real-time auction analytical heatmaps

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