Backend Engineer - Real-Time Auction Platform (Real Estate)

We are building a real estate auction platform from the ground up. The frontend is handled by us. We need a backend engineer to build the engine that powers it. This is a real-money, real-identity transactional system. Properties are listed, bidders register and verify their identity, deposits are collected, and live auctions run with real-time bidding, soft-close anti-sniping logic, and a legally defensible bid ledger. When the auction closes, the winner is notified and the buyer's premium is collected. What you are building: A real-time bidding engine with server-authoritative timestamps and concurrent bid resolution An identity and KYC layer using an official ID provider A deposit and payment lifecycle An append-only, hash-chained bid ledger that serves as the legal record of every auction A multi-channel notification system across email, SMS, and browser push An admin and operations layer for managing auctions, bidders, deposits, and post-close resolution We will NOT be using third party plugins for ownership and licensing reasons. The full technical scope is attached as a separate document. It covers every component in detail, including the specific questions you should answer as part of your proposal. Read the entire document before applying. Your proposal should answer every question inside it. Applications that do not reference the document or answer its questions will not be reviewed. Please start your reply to this listing with 'I have read and understand the project attachment'. You are a fit if you have: Built a real-time system using WebSockets in production Worked with Stripe payments, holds, refunds, and identity verification Designed and built systems where data integrity and audit trails were legally consequential Strong experience with Node.js or Python, PostgreSQL, and scalable backend architecture The ability to own the full backend architecture and not just execute tasks but make sound technical decisions independently. Read the attached scope document in full. Your proposal should include written answers to every question inside it, your proposed tech stack with justification, a simple diagram or written description of how the major components connect, your timeline and budget by phase, and your relevant work history with specific examples of real-time or financial systems you have built. Thanks, and we look forward to working with you!