Senior Mobile Engineer (React Native) AI-Driven Marketplace

Job Title

Senior/Staff Product Engineer (Mobile)

Company Description

Joinfleek.com – Post-Series B marketplace backed by a16z and YC

Location

London, UK

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.

Why this role is remarkable

• Direct ownership of the #1 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.

Required Skills

• E‑Commerce
• Software Engineering
• React Native
• Marketplaces
• Analytics
• A/B testing

Required Languages

• English

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