Machine Learning Engineer (up to £230k)

Dex; Greater London; On-site; GBP 90,000 - 120,000; Full time

Job summary

Dex is expanding its London data/ML function and seeking a hands-on ML engineer to ship production models. You will work across data pipelines, modeling, and live serving to influence user engagement and the company’s growth.

We value strong statistical expertise and a drive to deliver high-impact solutions that balance business value with technical elegance. This role focuses on practical ML infrastructure and scalable experimentation.

Qualifications

• Hands-on production ML experience shipping models end-to-end.
• Experience across data pipeline, model, and live serving.
• Strong grounding in statistics, including AB testing and probability.
• Interest in causal inference or uplift methods is a plus.
• Motivated by business impact as well as technical elegance.

Responsibilities

• Design and ship production ML models that impact user engagement and earnings.
• Translate business problems into ML formulations.
• Build and optimize reward/payout structures balancing cost and advertiser value.
• Diagnose and troubleshoot underperforming campaigns and implement fixes.
• Contribute to core ML infra, from training pipelines to live serving.

Skills

Production ML

End-to-end ML

Full stack ML

Statistics & AB testing

Infrastructure mindset

Job description

This role is with one of Dex's trusted partner companies. We work closely with their teams to truly understand their culture, goals, and what they're looking for, so we can match you with the right opportunity and give you context about the role before you commit to a process.

The role

This company runs a bootstrapped rewards platform with 80 million users, profitable since day one. The models you build here directly decide what users see and what the company earns, offering a rare, direct line from your work to significant business impact. They are one of Europe's fastest-growing companies, expanding their data and ML function in London.

The work

• Design and ship production machine learning models that directly impact user engagement and company earnings.
• Translate complex mathematical business problems into concrete ML formulations.
• Build and optimize reward and payout structures, balancing user motivation with cost sustainability and advertiser value.
• Diagnose and troubleshoot underperforming reward campaigns, identifying root causes and implementing solutions.
• Contribute to the design and implementation of the core ML infrastructure, from training pipelines to live model serving.

What You Bring

• You are genuinely hands-on in production ML, having shipped models end-to-end rather than handing them off.
• You work across the full stack of a problem: data pipeline, model, and live serving.
• You have a strong grounding in statistics, including A/B testing, regression, and probability, ideally with causal inference or uplift methods.
• You are motivated as much by business impact as by technical elegance, prioritizing high-leverage solutions.
• You want to build ML infrastructure alongside your team, not just use existing systems.