Senior Machine Learning Engineer (AdTech)

Location: Fully remote; available in Europe, Albania, Poland, Romania, Ukraine, Latin America, Argentina, Brazil, Colombia, and Mexico

Company

hirify.global Software provides engineering teams for technology projects, including large-scale programmatic advertising and machine learning platforms.

What you will do

• Build and validate predictive models for bid landscapes, conversion propensity, contextual over-indexing, and positive-unlabelled learning.
• Design offline evaluation frameworks using inverse propensity scoring, doubly robust estimators, exploration strategies, and propensity logging.
• Develop scalable training orchestration, model registry, publishing, and deployment workflows with lineage tracking, evaluation gates, and fallback procedures.
• Operate isolated per-advertiser models, shadow deployments, champion/challenger experiments, and freshness SLOs.
• Monitor feature and prediction drift, train/serve skew, calibration decay, and label latency in production.
• Document the platform, support knowledge transfer, and evaluate business impact through statistically grounded measurements.

Requirements

• 6+ years of combined commercial experience in Data Science and ML Engineering, including at least 2 years in each area.
• Expert Python and SQL skills, with strong production experience in machine learning systems.
• Strong practical experience with XGBoost, LightGBM, or CatBoost.
• Strong experience with MLOps, orchestration, CI/CD, model registries, Kubernetes, and Docker.
• Advanced knowledge of at least one area such as delayed labels, positive-unlabelled learning, off-policy evaluation, hierarchical estimation, or constrained optimization.
• Upper-Intermediate or higher English level; readiness to support operational ownership and participate in on-call activities.

Nice to have

• Experience in AdTech, RTB, ranking, pricing, or real-time marketplace systems.
• Knowledge of contextual bandits, multi-tenant ML systems, batch scoring, and freshness SLA requirements.
• Experience with MLflow, Kubeflow, Airflow, Argo, GCP, Vertex AI, BigQuery, Terraform, or on-premise Linux infrastructure.

Culture & Benefits

• Fully remote work with flexible collaboration across distributed teams.
• Engineering ownership and focus on technical excellence.
• Work on a high-load AdTech platform processing hundreds of millions of auction requests daily.
• Opportunity to solve complex machine learning challenges with measurable business impact.