Senior Machine Learning Engineer – Personalisation & Recommendations

About the Role

The Mar Tech 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.

• 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.

• 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, Tensor Flow, 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, No
  
  SQL stores).
• Bachelor’s, Master’s or PhD in Computer Science, Statistics, or a related field.
• Ad‑tech/Mar‑tech background is a plus.

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.

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.

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

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