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.