Senior Fullstack Engineer, Auctions

Alt is unlocking the value of alternative assets, starting with the $5 B trading-card market. We let collectors buy, sell, vault, and finance their cards in one place and we are backed by leaders at Stripe, Coinbase, Seven Seven Six, and pro athletes like Tom Brady and Giannis Antetokounmpo. Our next frontier is real-time pricing at scale—the Alt Value that powers every trade, loan, and product on the platform. We’re looking for a Senior Fullstack Engineer to build the engine behind a marketplace that moves hundreds of millions of dollars in GMV. Our Auctions team doesn't just "list items"—we build the high-stakes, high-concurrency environments where collectors’ dreams are realized. In this role, you’ll sit at the intersection of high-scale transaction systems and cutting-edge AI. You’ll build products that provide upfront liquidity to consignors, personalized discovery for buyers, and professional-grade tools for power sellers. If you’re energized by the idea of shipping features that millions of hobbyists and power-users rely on, we want to talk. What You’ll Do Here: Architect the Auction Engine: Build and scale the high-concurrency bidding and listing systems that power 9-figure annual GMV. Ship AI-Powered Liquidity: Develop next-gen features that leverage AI to provide instant valuations and upfront liquidity to our consignors and sellers. Personalize the Hobby: Use data and machine learning to build rich, personalized discovery experiences that match unique collectibles to the right buyers. Empower Power Users: Design and launch sophisticated management tools for everyone from high-frequency "power sellers" to veteran hobbyists. Own the Experience: Build end-to-end—from the low-latency backend logic required for live bidding to the sleek, responsive UI where the action happens. Drive Technical Excellence: Mentor the team and set the standard for code quality, system reliability, and performance. This is a perfect fit if you… Love High-Scale Challenges: You aren’t intimidated by 9-figure transaction volumes or the "thundering herd" of bidders in the final seconds of an auction. Are an AI Pragmatist: You know how to take LLMs or computer vision models and turn them into practical, user-facing features that solve real business problems. Think in Systems & UX: You can visualize how a data schema change on the backend will ripple out into the user experience for a power seller. Have High Agency: You thrive in an environment where you are expected to identify the highest-leverage work and execute on it without a hand-holding manual. What You Bring to the Table: 5+ years of experience building and scaling complex applications (Python, Postgres, AWS/Cloud infra). Modern Frontend Mastery: Deep experience with React, TypeScript, and building high-performance, real-time UIs. Data-Driven Mindset: Experience working with personalization engines, recommendation systems, or AI/ML integrations is a major plus. Product Instincts: You don’t just build what’s on the ticket; you understand the collector mindset and build features that delight them. Reliability Under Pressure: You have a track record of building systems that stay up when the stakes (and the traffic) are highest. What You’ll Get From Us: A seat at the table to help shape the future of Alt and the alternative asset space Autonomy and ownership on projects that matter $100/month work-from-home stipend $200/month wellness stipend WeWork office stipend 401(k) retirement benefits Flexible vacation policy Generous paid parental leave Competitive healthcare benefits, including HSA, for you and your dependent(s) Base salary range: $140,000-$180,000, plus equity. Offers may vary based on experience, location, and other factors.