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2025 Solo 2 weeks

BidArena

Real-Time Auction Platform — Supporting concurrent live bidding with JWT auth and Razorpay payments.

ReactTypeScriptNode.jsMongoDB

// the problem

Why build this?

Traditional auction platforms suffer from latency issues where users don't see bid updates in real-time, leading to poor user experience and unfair bidding outcomes.

// the solution

How I solved it

Built a WebSocket-powered architecture using Socket.io that broadcasts bid events instantly to all connected clients. Combined with automated lifecycle management using cron jobs for auction expiry, cleanup, and winner determination.

// architecture

System Design

React + TypeScript frontend
Node.js + Express backend
MongoDB database
Socket.io for real-time events
Razorpay payment gateway
node-cron for scheduled tasks

// features

Key Features

1

Real-time bid updates via WebSocket (Socket.io)

2

JWT authentication with secure session management

3

Razorpay payment integration for seamless transactions

4

Automated auction lifecycle (start, expire, finalize winner)

5

Background cron jobs for cleanup and expiry handling

6

Concurrent bidding support with race condition handling

// challenges & learnings

What I Learned

Handling race conditions when multiple users bid simultaneously

Designing reliable auction expiry with background cron jobs

Integrating Razorpay payment flow with auction winner determination

Interested in this project?

Check out the code on GitHub or try the live demo.