You will join the Growth squad to build the transaction layer for the world’s first digital supply chain for secondhand fashion. Reporting to the CTO (ex-Google, Postmates), you will integrate fine-tuned AI models into a B2B marketplace handling 500,000+ items monthly, turning manual trades into a structured, searchable global inventory layer.
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Senior Backend Software Engineer at Fleek
Join an a16z and YC-backed startup that is fixing the world's most broken supply chain by digitizing the $350B secondhand fashion market. Working directly under a CTO from Google and Postmates, you'll build the AI-native backbone for a platform that has already saved 9 million items from landfills and is tripling in size annually. This is a rare opportunity for a Senior Backend Engineer to own the entire ecommerce journey—from discovery to global payments—while integrating proprietary AI models into a high-scale B2B marketplace.
About this role
Role overview
About the company
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'll do
What you will do
- Architect and scale backend systems in Node.js and TypeScript to handle the transition from 500k to millions of unique items per month.
- Own the end-to-end ecommerce journey, including discovery, search, checkout, and complex international payment and credit systems.
- Collaborate with AI and data teams to bridge the gap between classification engines and the core marketplace product experience.
Who you are
Who this is a fit for
- 6–10 years of professional backend experience with strong fundamentals in system design and API architecture at high-growth consumer or marketplace companies.
- Proven product engineering mindset with a history of shipping end-to-end features in fast-paced, ambiguous startup environments.
- AI-forward builder who uses tools like Cursor or Copilot as a force multiplier and has experience deploying AI capabilities at scale.
Why this role
Why this role is remarkable
- Work at the intersection of circular economy and proprietary AI, using a fine-tuned model (not a GPT wrapper) to digitize a $350B industry that has never had technology.
- Massive financial backing with ~$50M raised from elite investors including a16z, Y Combinator, and HV Capital, plus advisors from Depop and Shopify.
- High-velocity environment where you will see immediate impact, helping save millions of garments from landfills while the company triples in size year-on-year.
Jack & Jill
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.
Meet Jack
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.
How does this work?
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 it’s a match and the company wants to meet you, they’ll make the intro. In the meantime, if you’d like, Jack will send you excellent alternatives.