Senior Machine Learning Engineer – Personalisation & Recommendations

Roku; Manchester; Hybrid; GBP 90,000 - 120,000; Full time

Benefits offered by this job

Mental health resources

Financial wellness resources

Healthcare

Life insurance

Disability insurance

Commuter benefits

Retirement options

Job summary

Roku is seeking a Senior Machine Learning Engineer in Manchester to tackle high‑impact MarTech challenges such as creative personalization and ad relevance. You will lead feature engineering, model training, and scalable inference across batch and streaming workloads, with a strong emphasis on production‑grade ML infra and performance tuning.

The role requires hands‑on coding in Python/Java and collaboration with engineering, product, data science, and commercial stakeholders.

Qualifications

• Applied machine learning experience on production systems.
• Experience with recommendations or sequential models is a plus.
• Strong background in statistics and experimental methodologies.

Responsibilities

• Data Analysis / Feature Engineering for multiple use cases and models.
• Train Machine Learning Models using techniques like recommendations, RL, trees, Bayesian methods, neural networks, transformers.
• Near Real-Time and Batch Inference using Spark and Ray.
• Build ML Infrastructure covering feature engineering, modeling, deployment and monitoring.
• Debug and optimize performance on large production clusters.

Skills

Data Analysis

Feature Engineering

ML Modeling

Python

Spark

Java

Ray

Statistics

Education

Bachelor/Master/PhD in CS/Statistics

Tools

Spark MLlib

Hive

NoSQL

TensorFlow

Job description

About the Role

The MarTech team at Roku is looking for a seasoned Senior Machine Learning Engineer with a strong background in machine learning and production systems. This role works on high‑impact problems across marketing and advertising, such as creative personalization, ad relevance, demographics inference, yield optimisation, and more. The position requires a strong foundation in experimental methodologies, statistics, recommendations, reinforcement learning, optimisation, probability theory, and machine learning. It involves coding for statistical analysis, tool building, and both general‑purpose software and statistical languages. The ideal candidate is a gritty problem‑solver and self‑starter, able to collaborate with engineering, product, data science, and commercial stakeholders. The role requires hybrid working from the Roku Manchester office.

What You'll Be Doing

• Data Analysis / Feature Engineering: Identify and calculate features for multiple use cases and models.
• Train Machine Learning Models: Apply techniques such as recommendations, reinforcement learning, decision trees, Bayesian analysis, neural networks, and transformers to develop and evaluate algorithms.
• Near Real‑Time and Batch Inferencing: Use Spark and Ray to set up inferencing services that integrate with operational and analytics workloads.
• ML Infrastructure: Build a first‑class machine learning platform from the ground up covering feature engineering, model training/evaluation, versioning, deployment/online serving, and monitoring prediction quality.
• Low‑Level Systems Debugging, Performance Measurement & Optimisation: Measure and optimise performance on large production clusters.

We're Excited If You Have

• First‑hand experience in applied machine learning on real recommendations use cases (productionized sequential learning is a plus).
• Experience with ML/distributed ML frameworks such as Ray, Spark‑MLlib, TensorFlow, etc.
• Experience with real‑time scoring/evaluation of models with low‑latency constraints.
• Strong coding skills and software development experience (Spark, Python, Java).
• Experience with large‑scale computing frameworks, data analysis systems, and modelling environments (Spark, Hive, NoSQL stores).
• Bachelor’s, Master’s or PhD in Computer Science, Statistics, or a related field.
• Ad‑tech/Mar‑tech background is a plus.

Benefits

Roku is committed to offering a diverse range of benefits to support employees and their families, including global access to mental health and financial wellness support and resources. Local benefits may include healthcare (medical, dental, vision), life, accident, disability, commuter, and retirement options (401(k)/pension). Employees can take time off in accordance with local leave policies.

Hybrid Work Approach

Roku fosters an inclusive and collaborative environment where teams work in the office Monday through Thursday. Fridays are flexible for remote work, except for roles required to be in the office five days a week.

Accommodations

Roku welcomes applicants of all backgrounds and provides reasonable accommodations and adjustments in accordance with applicable law. If you require reasonable accommodation at any point in the hiring process, please direct your inquiries to [e-mail].

Equal Employment Opportunity Statement

Roku welcomes applicants of all backgrounds and provides reasonable accommodations and adjustments in accordance with applicable law.