Remote Senior ML Engineer - AdTech Real-Time Bidding

SmartRecruiters, Inc.; Warszawa; Remote; PLN 180,000 - 360,000; Full time

Job summary

Sigma Software is seeking a Senior Machine Learning Engineer to join a distributed team building a predictive decisioning platform for a high-load AdTech live exchange. You will design, deploy, and maintain production ML models, scoring, and optimization pipelines with real-time requirements.

The role emphasizes collaboration across global teams, robust experimentation, and scalable infrastructure, including containerized builds and model registries.

Qualifications

• 6+ years of combined commercial experience in Data Science and ML Engineering, including at least 2 years in each area.
• Strong production experience with machine learning systems delivering measurable business impact.
• Deep expertise in Data Science/ML Engineering with solid hands-on competence in the complementary domain.
• Strong practical experience with gradient-boosted trees such as XGBoost, LightGBM, or CatBoost.
• Advanced knowledge in at least one of the following areas: delayed labels, PU learning, off-policy evaluation, hierarchical estimation, constrained optimization.
• Production-level Python and strong SQL skills.
• Hands-on experience with ML orchestration, CI/CD pipelines, and model registry management.
• Practical experience with Kubernetes and Docker in production environments.
• Strong experimentation and evaluation skills, including statistical interpretation of results.
• Readiness to support operational ownership and participate in on-call activities.
• Upper-Intermediate or higher English level.

Responsibilities

• Build and validate predictive models including advanced labeling strategies.
• Design offline evals using IPS and doubly robust estimators.
• Define exploration strategies and propensity logging.
• Calibrate models for advertisers while monitoring ranking and calibration.
• Develop and operate scalable training orchestration pipelines.
• Maintain model registry with lineage and gates.
• Isolate per-advertiser model instances.
• Own model publishing with freshness SLO.
• Run shadow deployments and champ/challenger experiments.
• Monitor drift and latency in production.
• Ensure reproducibility with pinned envs and containers.
• Participate in post-launch optimization using lift measurements.
• Prepare docs and knowledge transfer to Customer teams.

Skills

Production ML systems

English (Upper-Intermediate+)

On-call readiness

Python

SQL

Kubernetes

Docker

CI/CD

Model registry

ML orchestration

Experimentation

Tools

XGBoost/LightGBM/CatBoost

GCP Vertex AI

BigQuery

Kubeflow

Airflow

Argo

MLflow

Job description

Sigma Software is seeking a Senior Machine Learning Engineer to join a distributed team building a predictive decisioning platform for a high-load AdTech live exchange. You will design, deploy, and maintain production ML models, scoring, and optimization pipelines with real-time requirements.

The role emphasizes collaboration across global teams, robust experimentation, and scalable infrastructure, including containerized builds and model registries.