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Joinfleek.com

Joinfleek.com

Featured role

London, UKNot Disclosed
Featured roleLondon, UKNot Disclosed

Full-Stack Growth Builder at Joinfleek.comVC-backed B2B fashion marketplace

Joinfleek.com is looking for a Full-Stack Growth Builder to reinvent the $350B secondhand fashion market. Backed by $50M from a16z and Y Combinator, this London-based role isn't about running marketing campaigns—it's about architecting the AI-native intelligence behind global retention and lifecycle strategy. If you're a technical builder who treats AI as your default toolkit and wants to build systems that scale, this is your chance to lead growth at a generation-defining company alongside ex-Deliveroo and Shopify leaders.

Overview

Why this role stands out

Join a high-velocity team reinventing the secondhand supply chain. As a Full-Stack Growth Builder, you will architect AI-driven CRM systems and lifecycle strategies from the ground up. You’ll own the entire retention engine, building dynamic tools and experimentation frameworks that move beyond static journeys to drive measurable, causal growth for thousands of global resellers.

Company

Joinfleek.com

Joinfleek.com

joinfleek.com

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Technology100

Joinfleek.com - Series B fashion-tech marketplace backed by a16z and Y Combinator.

Responsibilities

What you will do

  • Architect and deploy adaptive, AI-powered CRM systems that determine optimal messaging, timing, and channels using real-time user signals.
  • Build end-to-end technical tooling for resellers, such as cross-listing features, to increase platform stickiness and long-term retention.
  • Design rigorous experimentation frameworks using causal inference and holdouts to quantify the true incremental impact of every growth initiative.

Candidate profile

Who this is a fit for

  • A deeply technical builder who uses AI-native tools like Cursor or Claude Code to ship production-quality full-stack systems at high velocity.
  • Strong analytical fluency in SQL and experience navigating large, messy datasets to derive actionable insights and experimental results.
  • Proven background in growth or product engineering with a focus on building automated decisioning systems rather than just managing marketing campaigns.

What makes it remarkable

Why this role is remarkable

  • Direct impact on sustainability by fixing the broken global supply chain for secondhand fashion, already saving 9 million items from landfills.
  • Work at a hyper-growth Series B startup that has raised ~$50M from premier investors including Andreessen Horowitz (a16z) and Y Combinator.
  • High-autonomy "super IC" role reporting to a VP of Growth (ex-Deliveroo) with the freedom to treat AI as your default development toolkit.

Jack & Jill

How Jack & Jill work together

Jack
I get to know what you’re great at, then find roles you’d never find yourself.
Jill
I recruit from Jack’s network and make the intro when I spot a great match.

About Jack & Jill

Meet Jack

Jack gets to know what you are great at, what you want next, and makes sure Jill considers you for the right opportunities.

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.

Learn more aboutJack

Ready to find your next role?

Talk to Jack for 10 minutes and see your first matches.