Online Auction System
Full-Stack Bid Platform
01 — Project Overview
An auction platform with live bid tracking, countdown timers, bidder auth, and a full seller admin panel.
Solo Developer — system design, backend, and UI.
Stack
02 — The Problem
Goal
Simulate a real auction experience in a browser with competitive bidding mechanics.
User Issue
Local community auctions lacked a digital platform for remote participation.
03 — The Process
Bid Locking
Used MySQL transactions to lock the current highest bid row during bid submission, preventing race conditions.
JS Countdown
Client-side countdown timers with server-side validation to prevent bids on expired auctions.
Key Challenge
Handling concurrent bids — two users submitting simultaneously could corrupt the highest-bid record.
$pdo->beginTransaction();
$top = $pdo->query("SELECT amount FROM bids WHERE item_id = $id ORDER BY amount DESC LIMIT 1 FOR UPDATE")->fetchColumn();
if ($newBid > $top) { /* insert */ }
$pdo->commit();04 — The Solution
A live auction platform with reliable bid locking, countdown timers, seller/bidder roles, and a clean UI.
05 — Results & Learnings
Impact
Successfully demonstrated race-condition-safe bidding logic using MySQL transactions.
Learnings
Learned the critical importance of database-level locking in any competitive real-time system.
What I'd do differently
Would add WebSocket-based live bid feeds so all bidders see new bids instantly without polling.