Senior/Staff Product Engineer (Mobile) at Joinfleek.com

  • Jack & Jill/External ATS
  • Mar 13, 2026
Full time Engineering

Job Description

Job Title

Senior/Staff Product Engineer (Mobile)

Company Description

- Post-Series B marketplace backed by a16z and YC

Job Description

As a Senior/Staff Product Engineer, you will own the mobile experience for the world's fastest-growing wholesale secondhand fashion marketplace. Joining the London-based Demand team, you will build the primary interface used by 90% of buyers, integrating AI-driven classification into a seamless, high-performance React Native application that directly drives global GMV.

Location

London, UK

Why this role is remarkable
  • Direct ownership of the revenue channel for a hyper growth startup tripling year-on-year with backing from top-tier VCs like a16z and Y Combinator.
  • High-impact architectural influence where you define the mobile standards and experimentation layers for a marketplace disrupting a fragmented supply chain across 70+ countries.
  • Work in an AI first engineering culture under leadership from Google and Postmates, utilizing cutting edge tools to solve complex inventory and discovery challenges.
What you will do
  • Lead the development of the core React Native application, focusing on high polish discovery, browsing, and purchasing flows that convert intent into transactions.
  • Partner with data and AI teams to implement mobile surfaces for the FleekSort classification engine, making complex AI grading feel intuitive for users.
  • Build and maintain a robust experimentation framework for A/B testing and analytics to drive data informed product decisions and optimize conversion rates.
The ideal candidate
  • 4-10+ years of professional software engineering experience with deep, production level expertise in React Native and mobile performance optimization.
  • Proven track record in a fast paced consumer marketplace or e commerce environment where interaction quality and animation polish are treated as core features.
  • Product minded engineer who leverages AI tools like Cursor or Copilot and connects technical trade-offs to commercial outcomes rather than just following tickets.