Senior Machine Learning Engineer (f/m/d)

Senior Machine Learning Engineer (f/m/d) - Job Description

Your Mission & Who We Are Looking For:

• 5+ years building production-grade recommendation systems. You’ve deployed large-scale systems in high-volume environments (adtech, e-commerce, or search), and have hands-on expertise in deep learning with TensorFlow, PyTorch, or JAX. At adjoe Ads, that means architecting high-throughput, low-latency systems that scale to 10 billion daily predictions.
• End-to-end model ownership. You own the full ML lifecycle from identifying relevant signals in large datasets and developing relevance models and bidding strategies, to rigorous monitoring, performance analysis, and iterative improvement in production.
• Engineer first, data scientist second. You write production-quality code, design for scalability, and collaborate closely with backend engineering teams to ensure seamless integration of reusable models and assets into the broader system.
• Experimentation is part of your workflow. You run rigorous A/B tests, validate hypotheses, and measure the impact of new features on key business metrics, not just offline evaluation.
• Plus: data engineering fluency. Understanding of data engineering principles and experience with distributed processing systems like Spark, Flink, or Kafka, and storage solutions like AWS Athena, S3, or MySQL is a strong plus.

What’s in It for You?

At adjoe, you’re not here to just close JIRA tickets, you’re helping build the infrastructure behind one of the most impactful platforms in adtech. The systems you work on will reach hundreds of millions of users and power billions of decisions every day.

• Go Big. Own projects with impact on 770M users and push adtech boundaries.
• Move Fast. Ship solutions multiple times a day, learn from results, and keep momentum.
• Be Direct. Solve problems openly and collaborate across teams.
• Thrive Together. Grow with a diverse, global team of people from over 40 different countries that learn from each other.
• Have Fun. Celebrate wins, enjoy daily victories, and bring your energy.

What You’ll Do / Responsibilities

• Own the full ML lifecycle for recommendation systems, from signal identification to model deployment and monitoring.
• Develop high-throughput, low-latency models for 10 billion daily predictions.
• Collaborate with backend engineers to integrate models and assets into the broader system.
• Conduct rigorous experiments and A/B tests to drive business impact.
• Work with distributed processing systems and large-scale data lakes (e.g., Spark, Flink, Kafka; AWS Athena/S3).

Team Description / Who You Are

Member of a data science team responsible for bidding algorithms, conversion prediction, and user quality estimation within a self-hosted ML ecosystem using PyTorch/TensorFlow. You thrive in a fast-moving environment with autonomy and cross-functional collaboration.

Tech Stack

• Modeling: PyTorch, TensorFlow, or JAX
• Data processing / tooling: Spark, Flink, Kafka
• Data storage / querying: AWS Athena, S3, MySQL
• Orchestration / pipelines: Airflow, Ray
• Data lake: Iceberg

Benefits & Perks

• Competitive salary
• Quarterly team adventures
• Monthly company feasts
• Up to €7000 for referred friends
• Discounted city commute
• Extensive visa & relocation support
• Hybrid work model
• Continuous investments in development
• Generous vacation days
• Mental health & wellness benefits