Company

Technology

SeniorMachineLearningEngineer,Search&Recommendations

CA$180k+ Bulgaria FULL TIME Remote Friendly
Market Sentiment
HIGH DEMAND

Neural analysis suggests this role is
optimal for Senior candidates.

The Brief

“Senior Machine Learning Engineer, Search & Recommendations. Skills: Machine Learning, Ranking systems, Recommendations, Optimization. Architect scalable ranking systems. Develop scalable ranking systems”

Industry & Context.

Technology

What They're Looking For.

Must Have

4+ years industry experience, 2+ years with PhD, Python proficiency, SQL proficiency, Pandas proficiency, TensorFlow experience, PyTorch experience, Gradient boosting experience, XGBoost experience, Ranking systems understanding, Personalization understanding, Recommendation architectures understanding, Online experimentation experience, A/B testing experience, Advanced evaluation methods experience, Multi-task learning architectures experience, Causal inference experience, Uplift modeling experience, Contextual bandits experience, Low-latency ML systems experience, Feature pipelines experience, Caching experience, Retrieval systems experience, Inference optimization experience

Nice to Have

LLMs for feature enrichment, LLMs for embeddings, LLMs for retrieval augmentation

What You'll Do.

Architect scalable ranking systems

Develop scalable ranking systems

Design multi-task learning models

Implement multi-task learning models

Build value-aware models

Build long-horizon models

Maximize incremental impact

Develop production-grade ranking pipelines

Maintain production-grade ranking pipelines

Develop inference systems

Maintain inference systems

Develop re-ranking layers

Maintain re-ranking layers

Develop constraint-aware decisioning

Maintain constraint-aware decisioning

Enhance search experiences

Enhance discovery experiences

Develop personalized autosuggest

Develop retrieval systems

Design online experiments

Execute online experiments

Design A/B testing frameworks

Execute A/B testing frameworks

Design counterfactual evaluation methods

Execute counterfactual evaluation methods

Collaborate cross-functionally

Translate business objectives

How You'll Work.

Team & Collaboration

Cross-functionally with Ads; Cross-functionally with Product; Cross-functionally with Infrastructure; Cross-functionally with Design

Full Job Description

## Accountabilities Architect and develop scalable ranking systems that unify search, recommendations, ads, and merchandising into a single multi-objective framework. Design and implement multi-task learning models (e.g., shared encoders, MMOE/PLE architectures) to jointly optimize relevance, conversion, margin, churn risk, and other business signals. Build and improve value-aware and long-horizon optimization models, including uplift and causal inference approaches to maximize incremental impact and LTV. Develop and maintain production-grade ranking pipelines, including inference systems, re-ranking layers, and constraint-aware decisioning. Enhance search and discovery experiences, including personalized autosuggest and retrieval systems powered by ML and LLM-enhanced features. Design and execute large-scale online experiments, A/B testing frameworks, and counterfactual evaluation methods to measure impact beyond short-term metrics. Collaborate cross-functionally with Ads, Product, Infrastructure, and Design teams to translate business objectives into ranking strategies and measurable outcomes. Mentor and guide other ML engineers on ranking systems, causal modeling, and scalable ML infrastructure. Requirements: 4+ years of industry experience applying machine learning at scale (or 2+ years with a PhD), with proven impact on ranking or recommendation systems. Strong experience with multi-objective optimization in production environments, balancing relevance, revenue, and user experience. Proficiency in Python and strong data skills using SQL, Pandas, and related tools. Hands-on experience with ML frameworks such as TensorFlow or PyTorch and classical ML methods like gradient boosting (e.g., XGBoost). Solid understanding of ranking systems, personalization, and recommendation architectures. Experience with online experimentation, A/B testing, and advanced evaluation methods beyond CTR-based metrics. Familiarity with multi-task learning architectures (MMOE, PLE, share

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