Live Shopping Platform

An auction that closes a second late, accepts a stale bid, or charges the wrong winner destroys trust immediately. Bid validation, auction countdowns, and payment capture cannot be left to the browser, yet everything has to stay synchronized across every connected device, including phones with drifting clocks, while video, commerce, and chat share one screen.

Post-sale logistics add marketplace-scale complexity: each winning bid becomes a real parcel with rates, labels, and customs for international orders, and the common case of one buyer winning several items from the same seller in one show. Meanwhile the money flow is two-sided: buyers are charged instantly, but sellers accumulate earnings that should only become withdrawable when the funds actually clear, minus commission and fees.

A single authoritative API process owns auction timers, bid validation, and payment capture. Clients receive state over Socket.IO and never decide outcomes locally. Every auction event carries a server timestamp, and the web client measures its clock offset and renders countdowns against server time, so a phone with a wrong clock still shows the true remaining seconds.

Concurrency is guarded at the database: auction start, auction finalisation, and giveaway draws are claimed through conditional MongoDB updates, so double-clicks, reconnects, and overlapping timers cannot start or settle the same auction twice.

Purpose-built services handle each concern, LiveKit for video transport and recording, Stripe for charging and seller payouts, Shippo for rates and labels, Firebase for chat and push, each wrapped behind the platform's own workflow logic, with all three clients consuming one documented REST and Socket.IO contract.

During a show, bids are validated server-side through an ordered rule chain, auction still open, bid actually higher, increment respected, bidder holds a valid payment method, with precise error events for each failure. Anti-snipe protection extends the countdown when a bid lands in the final ten seconds, and prebids and autobids let buyers set a maximum the system bids on their behalf, proxy-auction style. The moment an auction closes, the winner's stored card is charged off-session, a shipping rate is fetched, and the order is created; shows are recorded via LiveKit egress and the final seconds of each auction are automatically clipped with ffmpeg into a video receipt attached to the sold item.

Beyond auctions, hosts trigger timed flash sales with server-computed discounts, run giveaways with random winner draws, and negotiate through a full offer, counter-offer, and accept workflow where acceptance charges the card immediately. Shipping is bundle-aware: when a buyer wins multiple items from the same seller in one show, the items collapse into a single Shippo shipment under a weight cap and the buyer pays only the incremental shipping difference.

Every sale lands in a transaction ledger. Seller earnings accrue to a pending wallet and become withdrawable only when Stripe reports the funds as cleared, at which point idempotent transfers move money to the seller's connected account. A dedicated admin application covers seller approval, show and inventory oversight, an enforced order-status state machine, payouts, disputes, email campaigns, and a CMS for the public site.