Senior ML Data Engineer

Responsibilities

• Build and scale data pipelines that transform raw web-scale data into high-signal training datasets for AI research
• Develop algorithmic filtering, model-based quality scoring, and rigorous benchmark integrity mechanisms
• Maintain data processing pipelines including deduplication, PII masking, toxicity removal, metadata extraction, and proprietary transformations
• Ensure data compliance with governance policies and legal obligations
• Develop scoring and filtering tools using heuristics, LLM-as-a-judge, ML classifiers, and human-in-the-loop workflows
• Instrument pipelines with data quality monitoring, guardrails, and alerts to detect regressions
• Collaborate with Research and Legal teams to acquire and license large text corpora
• Design strict leak detection mechanisms to prevent evaluation contamination
• Build internal tools and interfaces for researchers to explore and query datasets

Requirements

• Degree in computer science, software engineering, or related field
• 5+ years of experience in data processing, ML engineering, or NLP
• Experience processing massive unstructured text datasets at trillion-token scale
• Hands-on experience with distributed processing frameworks (Spark, Ray, Flink)
• Experience implementing data privacy (PII masking), content safety filtering, and evaluation contamination prevention
• Proven ability to translate requirements from Research, Engineering, and Legal/Governance teams into pipeline work
• Strong Python skills for production-grade data processing
• Experience with pipeline orchestration frameworks (Airflow, Prefect, Dagster)

Preferred Qualifications

• Experience training, fine-tuning, or deploying ML models for data quality tasks
• Familiarity with LLM inference optimization (vLLM, SGLang)
• Familiarity with containerized deployment (Docker, Kubernetes) and infrastructure-as-code
• Familiarity with ML experiment tracking tools (Weights and Biases)
• Experience with data licensing workflows or web-scale data acquisition
• Contributions to open-source data processing or NLP tools

Benefits

• Comprehensive health benefits including mental health and wellness account
• 20 vacation days per year from hire date
• Employer 4% retirement savings contribution with no employee match required
• Additional 8% remuneration allocated to supplemental retirement savings or bonuses
• Collaborative and inclusive work environment in Montreal's Mile-Ex district

About the Company

LoiZéro is a nonprofit organization dedicated to advancing research and developing technical solutions for safe AI systems. Based in Montreal, it conducts research to design non-agentic AI systems that learn to understand the world through transparent, probabilistic reasoning.