You will join the Growth squad to own the core ecommerce journey, building backend systems for discovery, payments, and seller tools. Reporting to the CTO, you'll integrate the proprietary FleekSort AI classification engine into a marketplace handling millions of items. This role is about digitizing a broken, manual supply chain at global scale.
Senior Backend Software Engineer at Fleek
As a Senior Backend Engineer, you'll join a high-velocity Growth squad to build the AI-native infrastructure digitizing a global supply chain that has already saved 9 million items from landfill. Working directly with an ex-Google/Postmates CTO, you will integrate proprietary AI models to scale a platform tripling in size annually. This is a unique opportunity to own the transaction layer of a sustainable economy while shipping product-led features that define how the world trades secondhand goods.
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Location
London, United Kingdom
Compensation
£100k-£140k + Equity
Company
Fleek
Role overview
Technology100 employees
Fleek is a global online marketplace specializing in wholesale second-hand fashion. The platform connects retailers and resellers with verified vintage wholesalers around the world, making it easier to source high-quality used clothing in bulk. Fleek addresses the fragmented and often offline supply chain of vintage apparel by providing a transparent, secure, and scalable solution for both buyers and sellers. Founded in 2021, Fleek serves thousands of resellers and retailers in over 70 countries, moving millions of vintage clothing items from a vast network of wholesale suppliers. The company is backed by prominent investors, including Y Combinator, and has raised significant funding to expand its market reach and technical capabilities.
What you will do
- Architect and own the end-to-end ecommerce journey, including item discovery, search, multi-currency payment systems, and credit infrastructure.
- Design and scale backend services to handle over 1 million unique items per month, connecting AI grading engines to real-time marketplace workflows.
- Collaborate in a senior product squad to translate complex international logistics and supply chain challenges into reliable, high-performance software.
Who this is a fit for
- Has 6-10 years of professional backend experience, ideally using Node.js and TypeScript, with a proven track record of shipping high-traffic production systems.
- Possesses a product engineering mindset from a consumer-facing marketplace or fintech background, focusing on commercial outcomes rather than just infrastructure.
- Thrives in early-stage, fast-paced environments (Seed to Series B) and utilizes AI tools like Cursor or Copilot as a force multiplier in their workflow.
Why this role is remarkable
- Work on a genuinely novel technical challenge by integrating FleekSort, a custom AI model (not a GPT wrapper) that digitizes opaque secondhand inventory.
- Join a hyper-growth company tripling year-on-year with ~$50M in funding from top-tier investors like a16z, Y Combinator, and HV Capital.
- Deliver massive environmental impact by building systems that have already saved 9 million items from landfills and are scaling to serve thousands of global retailers.
How Jack & Jill work together
I get to know what you’re great at, then find roles you’d never find yourself.Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.
I recruit from Jack’s network and make the intro when I spot a great match.And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.
Jack gets to know what you're great at and what you want next, then searches 15 million jobs daily and helps you discover roles at companies like this.
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What happens next?
Jack’s an AI agent for job searching and career coaching. He works for you.
Jill is the AI recruiter working for the company. She recruits from Jack’s network.
If your profile’s a match and Fleek wants to meet, Jill will make the intro. In the meantime, Jack will send you excellent alternatives.