3. Build a Whatnot-Style Live Auction App — Mobile, Live Video, Escrow Payments

We are building a mobile live commerce app for the Turkish market — sellers run live video broadcasts and auction items one at a time, buyers bid in real time and pay at the end of the show. The closest reference is Whatnot. Product design is finished. We have 30+ working screen mockups, locked business rules, a defined category schema and a selected payment provider. This is an engineering job, not a product design job. Scope Native iOS and Android app (primary surface) Live video streaming — seller capture, viewer playback, still-frame capture from the running stream Real-time bidding engine — server-authoritative clock, anti-sniping, 30–90 second lots, high concurrency Marketplace payments — hosted checkout, card tokenisation, stored-card charging, submerchant payouts, escrow release controlled by platform logic Shipping API — label generation, tracking, combined shipments Bulk listing — rapid camera capture, gallery multi-select with grouping, spreadsheet import AI layer — attribute suggestion from photos (selecting from a fixed schema, not free text), chat moderation Web admin panel — five roles, action logging, live monitoring, disputes, payouts, reconciliation The hard part Many simultaneous bids on a single item, on a 30-second clock, with correct money movement. If your team has not handled concurrency and financial consistency before, please say so — we would rather know now. Please include in your proposal 1 - Fixed-price quotation broken down by workstream, with estimated hours 2- Phased timeline in weeks — we prefer a narrower first release sooner 3- Team composition and CVs, specifically who owns the bidding engine and who owns payments 4- How many other projects that team is running in parallel Which parts of this scope would be new to your team 5- A live production system with payment integration you have delivered We do not expect you to know Turkish regulation — legal requirements are documented on our side and will be supplied. Please do not price for legal research. Questions before you quote are welcome.