Senior Machine Learning Engineer (f/m/d)

Reposted 16 Days Ago
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Hamburg, DEU
Hybrid
Senior level
AdTech
Building innovative technologies to redefine advertising and monetization.
The Role
Design, build, and productionize large-scale recommendation and bidding ML models. Own the full ML lifecycle from feature discovery and training to deployment, real-time low-latency inference, monitoring, and A/B experimentation. Collaborate with backend and data engineering teams to integrate models and iterate on performance.
Summary Generated by Built In

adjoe builds the technologies behind mobile apps growth and monetization. adjoe Ads is our programmatic in-app advertising platform that seamlessly connects advertisers and publishers through direct integration of our Android and iOS SDKs. Every ad decision happens in under 200ms across 10 million daily users, powered by real-time bidding algorithms and user quality prediction models that match the right ad to the right user at the right moment.

50 Billion Daily Bid Predictions

The adjoe Ads Data Science team owns the entire bidding algorithm that decides which ad you are most likely to enjoy from start to finish: conversion prediction, user quality estimation, and bid shading. Every bid adjoe placed in an ad auction is the output of ML models making 50 billion predictions daily, trained on data from our mobile SDKs that capture real user behavior at scale.

The team moves fast: new ideas tested offline, A/B tests launched in production within minutes. We rely on industry-proven state of the art technology, adapted to our needs and self-hosted where it matters: PyTorch and TensorFlow for modeling, Trino and Athena for querying a 350TB Iceberg data lake, Airflow and Ray for orchestrating our different training pipelines across multiple GPU clusters. Models are built on 600+ features and trained on 200 million data points, with the full ML lifecycle owned by the team from research and experimentation to deployment and real-time inference at sub-200ms latency.

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.

🌎 We welcome applications from talent worldwide and provide relocation support to Hamburg, Germany for those ready to join our team.

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.

We welcome applications from people who will contribute to the diversity of our company.

Skills Required

  • 5+ years building production-grade recommendation systems or similar large-scale ML systems
  • Hands-on expertise in deep learning with TensorFlow, PyTorch, or JAX
  • Experience deploying high-throughput, low-latency ML systems in production (adtech, e-commerce, or search)
  • Ownership of the full ML lifecycle including monitoring, performance analysis, and running A/B tests
  • Strong software engineering skills; write production-quality code and integrate models with backend systems
  • Data engineering fluency and experience with distributed processing/storage (Spark, Flink, Kafka, AWS Athena, S3, MySQL)
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The Company
HQ: Hamburg
200 Employees
Year Founded: 2018

What We Do

adjoe is a leading advertising and monetization platform providing publishers and advertisers with cutting-edge solutions to engage their audience and scale their business. By harnessing the power of rewarded engagement and premium targeting we help advertisers reach their most valuable users. adjoe’s proprietary technologies give publishers the opportunity to level up their current monetization strategies in order to create a meaningful engagement loop for users and grow revenue.

Why Work With Us

Despite our diverse nationalities and backgrounds, we work with one mindset, one goal, five values – and with a lot of fun. Whether that’s from our modern office in the city center or from home. Besides working in tight-knit teams, we trust you to own your learning, tasks, and technology to make great things happen.

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