About the role: Circlin is building a video-first, mobile-first secondhand marketplace designed to make buying and selling easier, safer, and more engaging. We're looking for a Founding Backend Engineer to help build the systems at the core of the product. This is an early, high-ownership role. You’ll work closely with a small team and help shape how the marketplace handles orders, payouts, search, messaging, notifications, integrations, and the operational edge cases that matter in production. Compensation: This is a founding, equity-only role initially. There is no cash salary before fundraising. If we raise, we expect the role to transition to salary + equity, subject to financing and final agreement. Location: Europe-based preferred. Switzerland strongly preferred. What you’ll work on: - Design, build, and operate production backend services and workflows - Own backend architecture decisions across APIs, workers, events, and external integrations - Build resilient systems around payments, shipping, search, messaging, and marketplace workflows - Define how we handle idempotency, retries, duplicate events, consistency, and payouts safely - Help shape the engineering culture, quality bar, and long-term backend foundations of the company You might be a fit if you: - Have strong TypeScript / Node.js backend fundamentals - Have built and operated production backend systems from scratch - Have hands-on AWS & Azure experience in real-world systems - Care deeply about correctness, edge cases, and production behavior - Communicate clearly and make sound technical tradeoffs - Want real ownership in an early-stage company Especially relevant experience: - Marketplace or e-commerce backends - Event-driven systems - Payment systems and webhooks - Search infrastructure - Recommendation, feed, or personalization systems Why this role is interesting: - Founding-level ownership - Direct influence over architecture, engineering standards, and product velocity - A chance to help define the company while it is still early