Senior Software Engineer

About the role

You own complex challenges from intake to shipping, designing systems that handle routing logic and real-time optimization for major partners. We build tools for Vinted, TikTok, and Temu while maintaining a culture of first-principles thinking. Your work defines how goods transition in the online environment.

Key facts

What you'll do

Designing end-to-end workflows that transform cargo data into intelligent routing decisions.

Creating intuitive operational tools using Flutter and TypeScript to streamline human tasks.

Analyzing thousands of data points to refine models that cut friction from online commerce.

Shipping production code weekly, often daily, to support fast-growing e-commerce platforms.

Integrating with cloud infrastructure on GCP, using BigQuery and Cloud Run for scalable solutions.

Partnering with robotics and IoT teams to test emerging tech that powers logistics operations.

Translating feedback from data scientists into reliable services for marketplace platforms.

Championing reliability by writing code that meets strict standards for speed and accuracy.

Requirements

You must have experience with Python, Rust, and TypeScript to build resilient services.

You need more than three years in industry, demonstrating skill with distributed systems and hardware architecture.

You must understand logistics constraints so models reflect real-world limitations and opportunities.

You need experience handling large-scale ML inference and data modeling for high-volume flows.

Nice to have

No preferred items specified.

Skills & tools

Python; Rust; TypeScript; Flutter; BigQuery; Cloud Run; ML modeling; LLM inference; robotics; IoT

Practical notes

Work hours are standard; travel is not required; visa sponsorship is available for roles in London.

THE TEAM

Our structure includes approximately 110 people, with more than half focused on engineering, product, and data. We have assembled over 45 advanced degrees in computer science, mathematics, and operations research. Every day, we capture, calculate, analyze, and predict data for each parcel we handle. Our culture emphasizes first-principles thinking, tight feedback loops, and relentless experimentation.

Work Alongside Industry Leaders

Diego Protas

Director of Engineering

Diego brings deep expertise in distributed systems and hardware architecture, merging physical computing with enterprise-scale infrastructure. He previously directed teams of 170+ engineers at Mercado Libre and managed large-scale ML-based inference at Meta. At Relay, his hands-on leadership and enthusiasm redefine expectations for speed and reliability.

Tech Stack Highlights

• Python, Rust and TypeScript - we keep things simple but use the right tool for the job
• Cross-platform Flutter apps with a deep focus on user experience
• Cloud-native on GCP with extensive use of BigQuery and Cloud Run
• Extensive use of ML modelling and LLM inference - this is our daily routine
• Emerging tech integrations, including robotics and IoT-powered operations

The Opportunity

At Relay, you will own challenging, impactful problems end-to-end, from routing algorithms to real-time optimisation services and intuitive operational tools. You will collaborate closely with top engineers, data scientists, and product leaders in a highly autonomous and impact-driven environment. You will ship production-quality code weekly-and often daily-seeing your work directly impact Relay's growth. Your contributions will help power the fastest-growing e-commerce platforms, including Vinted, TikTok, and Temu, impacting millions of users worldwide.

Fast and Focused Hiring Process

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.

Compensation, Benefits & Workplace

• Generous equity, richer than 99% of European startups, with annual top-ups to share Relay's success.
• Private health & dental coverage, so comprehensive you'd need to be a partner at a Magic Circle law firm to match it.
• 25 days of holidays
• Enhanced parental leave.
• Located in Shoreditch, our office set-up enables the kind of in-person interactions that drive impact. We work 4 days on-site, with 1 day remote.
• Hardware of your choice.
• Extensive perks (gym subsidies, cycle-to-work, Friday office lunch, covered Uber home and dinner for late nights, and more).

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 us connect.

Relay is an equal-opportunity employer committed to diversity, inclusion, and fostering a workplace where everyone thrives.

About the company

Relay is building the web3 messenger. We are looking for talented and motivated front-end engineers of all experience levels. Relay engineers thrive in a high-growth, high-velocity environment where success depends on the highest levels of communication, code quality, and pragmatism.