Hybrid Principal ML Engineer — Paris/Barcelona

Harnham; Barcelona; Hybrid; EUR 81,000 - 135,000; Full time

Benefits offered by this job

Salary up to €135,000

Job summary

Harnham is seeking a Principal Machine Learning Engineer for a high-growth AdTech scale-up with ML at the heart of the product. You will report to the CTO, shape technical strategy, and lead cross-team ML initiatives while staying hands-on in model development that powers real-time bidding and attribution.

You will guide ML direction, design production systems, mentor engineers and drive MLOps and observability, aligning technical work with commercial goals across global teams.

Qualifications

• Senior, Staff or Principal ML Engineer with production experience.
• Proven track record deploying ML systems at scale.
• Experience in AdTech, programmatic advertising or DSP is highly desirable.
• Strong Python and ML engineering skills; PyTorch or TensorFlow proficiency.

Responsibilities

• Define technical direction and influence ML strategy across teams.
• Design, build and deploy ML models in production environments.
• Develop recommendation, bidding, attribution and churn models.
• Scale ML infrastructure, experimentation platforms and training pipelines.
• Mentor engineers and contribute to architecture decisions.

Skills

Machine Learning Engineer

Python

MLOps

Tools

PyTorch

TensorFlow

Job description

Harnham is seeking a Principal Machine Learning Engineer for a high-growth AdTech scale-up with ML at the heart of the product. You will report to the CTO, shape technical strategy, and lead cross-team ML initiatives while staying hands-on in model development that powers real-time bidding and attribution.

You will guide ML direction, design production systems, mentor engineers and drive MLOps and observability, aligning technical work with commercial goals across global teams.