Job Specifications
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 Mobile Engineer role on Fleek's Demand team — the function responsible for growth, conversion, and customer experience. You'll work closely with the Staff Engineer for Demand and partner deeply with Product and Design in London.
You'll own the mobile experience that buyers interact with daily. If it affects how a buyer discovers, evaluates, or purchases inventory on Fleek — it runs through your code.
Why This Role Stands Out
Mobile is the primary surface for Fleek's buyer experience. You won't be maintaining an app — you'll be building the product that converts intent into transactions across a marketplace unlike anything that's existed before.
Every item on Fleek is unique. Inventory is graded by AI, sourced from multiple countries, and moves fast. The mobile experience needs to make this complexity feel effortless — fast browsing, intelligent discovery, seamless purchasing. You'll work closely with our data and AI teams to bring FleekSort's classification engine into the buyer's hands.
This isn't a feature factory. You'll be shaping product decisions, challenging design trade-offs, and defining the mobile architecture for a marketplace that's tripling year-on-year. The Demand team in London is small, senior, and moves fast.
What Makes You a Fleek Mobile Engineer?
Craft-Obsessed Builder: You care about interaction quality, animation polish, and the 50ms that separates a good experience from a great one. You connect UI decisions to conversion outcomes.
Product-Minded, Not Ticket-Minded: You think about why a buyer drops off mid-scroll, not just what the spec says. You instinctively connect technical decisions to commercial impact.
Comfortable with Ambiguity: We're building mobile experiences for workflows that didn't exist before Fleek. You thrive when the problem is undefined and collaboration is key.
Owner, Not Renter: You take a feature from problem definition to production and monitor it afterwards. You don't wait for someone to hand you a Jira ticket.
Startup Pace: You've worked in environments where shipping matters more than perfection, where you release weekly, and where velocity is a competitive advantage.
What You'll Do
Own the Mobile Buyer Experience: Build and scale the React Native app that powers Fleek's core marketplace — browsing, discovery, purchasing, and post-purchase. These are the flows that directly drive GMV.
Integrate AI into the Product: Build the mobile surfaces that bring FleekSort's AI classification engine to buyers — ensuring grading, pricing, and categorisation translate into intuitive, fast, and trustworthy UX.
Ship with Craft and Velocity: Maintain release stability, reduce crash rates, and improve performance across devices — while shipping new features at startup pace. We optimise for velocity without fragility.
Shape Product Direction: Work embedded with Product and Design to define what gets built. Challenge assumptions, propose alternatives, and bring technical trade-offs into product conversations early.
Build the Experimentation Layer: Instrument the mobile app for A/B testing and analytics. Create the surfaces that let the Demand team run experiments and make data-driven product decisions.
Raise the Bar: Contribute to architectural decisions, improve code quali