Auction-Based E-Commerce Platform
A backend-heavy commerce platform combining time-bound auction flows, Razorpay payments, and Zoom-powered live sessions — letting sellers present items in real time while buyers bid and transact in the same flow.
Tech Stack
Responsibilities
- Designed and shipped the full auction lifecycle API — open, active bidding, close, winner resolution, and payment trigger
- Handled bid concurrency with server-side validation to resolve simultaneous bids at the same price point
- Integrated Razorpay to trigger payment collection automatically on auction close for the winning bid
- Embedded Zoom SDK to enable live seller sessions, letting hosts present items in real time during active auctions
- Built commerce APIs for non-auction direct purchases alongside the bidding flow
Case Study
Standard e-commerce assumes a fixed price and an add-to-cart flow. This platform needed a fundamentally different model: time-bound auctions where the price is determined by competitive bidding, with the added context of a live seller session running in parallel so buyers could see the item presented in real time before committing.
The auction lifecycle moved through defined states: open — accepting registrations and pre-bids; active — live bidding window; closed — winner resolved, payment triggered; settled — payment confirmed, item dispatched. Each transition was server-driven with strict validation to prevent bids arriving outside the active window or after a close event had already been processed.
The hardest engineering problem in an auction is concurrency: two bidders placing the same amount at the same millisecond. I handled this at the API layer with optimistic locking — bids were accepted only if the incoming amount was strictly greater than the current highest bid at the moment the write committed, turning a race condition into a deterministic rejection with a clear retry path for the losing bid.
Razorpay was integrated to trigger payment collection automatically when an auction closed. Rather than asking the winner to manually initiate payment, the system generated a payment link and pushed it to the winner's session the moment the closing event fired. Zoom SDK was embedded to run live seller sessions alongside active auctions — the host could present the item, field questions, and drive bidding from a single interface without switching tools.