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Relay Technologies

Senior Machine Learning Engineer

London - Hybrid
Level
Senior
Work type
Hybrid · London

Not stated in the posting: salary, visa.

Open. First seen 3 October 2026.

Apply on the company's site →

About the role

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, and a recently closed Series B ($95M), Relay is scaling faster than 99% of venture-backed startups. We're assembling the most talent-dense team the logistics industry has ever seen

Relay Technologies's standard text

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

Relay Technologies's standard text
  • ~160 people, around 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

Every parcel Relay handles is touched by ML. We recommend and optimise route assignment, predict delivery durations, estimate parcel dimensions and weight, detect objects in images on device, forecast demand and decide network handovers. That's 10+ models running in the critical path of a live logistics network where quality is non-negotiable.

ML Stack Highlights

  • Python and Rust. We keep things simple but use the right tool for the job
  • Rust with ONNX in-process model execution where throughput is critical
  • Chalk.ai as our Feature Store
  • GCP Agent Platform Endpoints for model serving
  • Cloud-native on GCP. Services run on Kubernetes, with extensive use of BigQuery

The Opportunity

As a Senior Machine Learning Engineer at Relay, you'll:

  • Own critical part of ML: productionising of our models end-to-end, from training pipeline through live integration to measured business impact.
  • Build and mature our ML Platform. Evolve the model serving architecture, expand reusable components adoption and set the standards for how Relay ships ML org-wide.
  • Strengthen existing models by architecting integration and system testing within training pipelines, automated releases and drift monitoring.
  • Launch completely revamped processes side by side with data scientists and measure their real-world impact on the network.

We're looking for candidates who…

  • Have at least two years deploying and operating models in production and four years building software on high-performing teams.
  • Are comfortable diving into unfamiliar codebases and languages to ship a model into a live system.
  • Prefer building the automation that removes manual labour over repeating it.
Relay Technologies's standard text

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.

What this role asks for

Particular to this role

GCP · Kubernetes

Rare in Relay Technologies's other 10 open postings.

Standard for data science / ML roles

Machine Learning · Python

Common in data science / ML postings at any company.

53% of this description is written for the role. The rest is Relay Technologies's standard text, folded away below.

Read against Relay Technologies's other open postings on this site.

The team: Engineering

This role is one of 3 open in Engineering.

WHAT THE TEAM WORKS WITH, ACROSS ITS POSTINGS

BigQuery (2 of 3), GCP (2 of 3), Machine Learning (2 of 3), Python (2 of 3), Rust (2 of 3)

OTHER ROLES ON THIS TEAM

From the team and dates on Relay Technologies's own job board.

Salary context

47 other open postings titled Senior Machine Learning Engineer state a salary: median USD 184,700 to USD 250,000 a year.

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