Senior Full Stack Engineer

Senior Full Stack Engineer Can you help us fix the world's most broken supply chain? The fashion industry produces over 100 billion garments a year. 60% end up in landfill, not because people don't want these clothes, but because the supply chain for getting secondhand fashion from donation to resale is completely offline, manual, and broken. Fleek is fixing this. Our mission is to make secondhand the first choice. We're building the infrastructure powering the global secondhand clothing trade, through a B2B marketplace and the AI systems digitising the supply chain behind it. Through Fleek, vintage stores, online resellers, and retail buyers source graded secondhand inventory directly from wholesalers and rag houses across multiple countries. Our key enabler is FleekSort, an AI model fine-tuned on secondhand fashion, that can grade, price, and categorise items with just a photo, turning what has historically been an opaque and manual trade into a structured, searchable, and tradable global inventory layer. Since 2022, we've saved 9 million items from landfill and tripled in size year-on-year. We've raised ~$50M from a16z, Y Combinator, Burda Principal Investments, HV Capital, and others, and have recently closed our Series B. Our advisors and private investors include operators behind Depop, Shopify, and Postmates. Today, we serve thousands of resellers and retailers across the UK, Europe, and the US. With the secondhand fashion market projected to reach $350B by 2027, Fleek is building the AI-native operational and financial backbone for secondhand commerce globally. We're looking for people who want to build something that matters, and move fast doing it. Sound good? Keep reading. About the Role This is a Senior Full Stack Engineer role in Fleek's product engineering team, with a frontend lean. You'll report into our CTO, Sanket Agarwal https://www.linkedin.com/in/sanket-agarwal-32209641/ (ex-Google, Postmates), and work embedded with a product manager and designer in a small, senior squad focused on user growth and the core consumer experience. Why This Role Stands Out Fleek is building a social, video-first marketplace where every item is unique, supply is unpredictable, and the buying experience has to work for professional resellers making high-volume purchasing decisions and first-time buyers exploring a market they've never seen before. You will be on our Growth team, rebuilding core user journeys from first principles, the discovery experience, the buying flow, seller onboarding, and the mobile app that's becoming an increasingly critical surface. You'll run your own experiments, interrogate your own data, and ship features that move metrics you can see. When you improve activation by 5%, you'll watch it in the revenue numbers the same week. The platform handles 500,000+ items a month across web and mobile today and million+ by the end of the year, with AI-powered grading and pricing integrated throughout the experience. You'll work across both React (web) and React Native (mobile), and you'll be expected to reach into the backend when the feature demands it. We're looking for a product engineer who thinks about user behaviour, commercial impact, and growth mechanics, and ships fast enough to test their hypotheses. You'll be expected to understand the business problems your code solves, and challenge whether we're solving the right ones. What Makes You a Fleek Full Stack Engineer? - Growth-Wired: You think in funnels, activation loops, and conversion rates. You've shipped features that directly moved user acquisition, retention, or revenue, and you can point to the numbers. - Design Partner: You work with designers, challenge UX decisions, and suggest improvements based on what you see in the data. You care deeply about how an experience feels. - Customer-Focused Thinker: You've built for end users at scale. You understand how technical choices affect customers and the broader product experience. - ... (truncated, view full listing at source)