Senior Machine Learning Engineer - Messaging Platform

Responsibilities

• Design, build, and ship machine learning models that optimize messaging across push, email, and in-app channels.
• Plan and run A/B experiments in a multi-objective environment, balancing conversion, engagement, retention, and reachability.
• Contribute to reinforcement learning systems that optimize for long-term user outcomes rather than immediate interactions.
• Partner with product managers, data scientists, and engineers to define success criteria and measurement approaches.
• Own the full ML lifecycle, from data and modeling to deployment, monitoring, and iteration.
• Integrate ML models with upstream systems, including domain value signals and opportunity generation frameworks.
• Explore AI-assisted development tools to accelerate experimentation and delivery.

Requirements

• Strong experience building and deploying machine learning models in production environments at scale.
• Ability to translate business problems into ML solutions and discuss trade-offs with cross-functional partners.
• Experience with complex optimization problems such as ranking systems or multi-objective decision-making.
• Hands-on experience with PyTorch and distributed systems such as Ray or similar frameworks.
• Deep understanding of experimentation and reliable testing in environments with interacting metrics.
• Ability to analyze results using approaches such as causal inference or metric decomposition.
• Experience with, or curiosity about, reinforcement learning and long-term optimization systems.
• Ability to work across disciplines, navigate ambiguity, and shape strategy and direction.

Work Arrangement

• Based in London and Stockholm.
• Hybrid flexibility with some in-person meetings and the option to work from home.