Senior Mobile Engineer

Title: Senior Mobile Engineer Location: London - Hybrid Relay is fundamentally reshaping how goods move in an online era. Backed by Europe’s largest-ever logistics Series A ($35M), led by deep-tech investors Plural (whose portfolio spans fusion energy and space exploration), Relay is scaling faster than 99.98% of venture-backed startups. We're assembling the most talent-dense team the logistics industry has ever seen Relay’s Mission is to free commerce from friction. Today, high delivery costs act as a hidden tax on e-commerce, quietly shaping what can be sold online and limiting who can participate. We envision a world where more goods move more freely between more people, making the online shopping experience seamless and accessible to everyone. THE TEAM · ~110 people, more than half in engineering, product and data · 45+ advanced degrees across computer science, mathematics and operations research · Thousands of data points captured, calculated, analysed and predicted for every single parcel we handle · An intellectually vibrant culture of first‑principles thinking, tight feedback loops and relentless experimentation Work Alongside Industry Leaders Diego Protas – Director of Engineering Diego, an expert in distributed systems and hardware architecture, merging physical computing with enterprise-scale infrastructure. Previously directing teams of 170+ engineers at Mercado Libre and orchestrating large-scale ML-based inference at Meta. At Relay, Diego’s infectious enthusiasm and hands-on leadership are redefining the boundaries of speed and reliability. Tech Stack Highlights - Cross-platform Flutter apps with a deep focus on user experience - Python, Rust and TypeScript - we keep things simple but use the right tool for the job - Cloud-native on GCP with extensive use of BigQuery and Cloud Run - Extensive use of ML modelling and LLM inference - no gimmicks here, this is our daily routine - Emerging tech integrations, including robotics and IoT-powered operations What you'll do - Work across the full stack of technology, from mobile all the way down through data infrastructure. - Take end-to-end ownership over thorny real-world problems, like using machine vision to automatically assess proof of delivery photos. - Collaborate with team members across the company. - Regularly spend time in the field learning how the technology you build impacts our couriers and parcel recipients. Fast and Focused Hiring Process 1. Talent Acquisition Interview - 30 min 2. Build a UI Component Interview - 1 hour 3. Design and Mobile Fundamentals Interview + AI Programming (Build an APP) - 2 hours 4. Operating Principles & Impact - 1 hour 5. Decision and offer within 48 hours, our process mirrors our pace of work, typically completed in a week. Who Thrives at Relay? - Aim with Precision: You define problems clearly and measure your impact meticulously. - Play to Win: You chase bold bets, tackle the hard stuff, and view constraints as fuel, not friction. - 1% Better Every Day: You believe that small, consistent improvements lead to exponential growth. You move quickly, deliver results, and learn from every experience. - All In, All the Time: You show up and step up. You take ownership from start to finish and do what it takes to deliver when it counts. - People-Powered Greatness: You invest in your teammates. You give and receive feedback with care and candour. You build trust through high standards and shared success. - Grow the Whole Pie: You seek out win-win solutions for merchants, couriers, and our customers, because when they thrive, so do we. If these resonate, and you combine strong technical fundamentals with entrepreneurial drive, let’s connect. Relay is an equal-opportunity employer committed to diversity, inclusion, and fostering a workplace where everyone thrives.