Senior Machine Learning Engineer (AI)

TL;DR

Senior Machine Learning Engineer (AI): Designing and building production ML systems for recommendations, search, and advertising at internet scale with an accent on end-to-end ML lifecycles and LLM-driven experiences. Focus on improving ranking, relevance, and monetization through deep learning and large-scale data pipelines.

Location: Remote (Ontario, Canada)

Company

Reddit is a community-driven platform for open and authentic conversations across 100,000+ active communities.

What you will do

• Design and deploy production-grade ML models for personalized recommendations and search ranking.
• Build scalable data and model pipelines with high reliability and automated retraining.
• Develop intelligent advertising systems, including bidding, measurement, and optimization.
• Research and apply state-of-the-art techniques, including Transformers, GNNs, and LLM alignment.
• Collaborate cross-functionally with Product, Data Science, and Engineering teams to translate business problems into technical solutions.

Requirements

• 3-5+ years of experience operating machine learning systems in production.
• Proficiency in Python, Java, or Go with solid software engineering fundamentals.
• Strong grasp of ML algorithms, from XGBoost and Random Forests to DL architectures (Transformers, CNNs, GNNs).
• Hands-on experience with PyTorch or TensorFlow.
• Must be based in Ontario, Canada.

Nice to have

• Experience with recommender systems, search/ranking, or advertising/auction systems.
• Familiarity with distributed systems and data processing tools like Spark, Kafka, Ray, Airflow, or BigQuery.
• Expertise in LLM/Gen AI techniques, including RAG, fine-tuning, and knowledge distillation.
• Advanced degree in Computer Science, Machine Learning, or a related quantitative field.

Culture & Benefits

• Comprehensive healthcare benefits and income replacement programs.
• 401k with employer match.
• Flexible vacation and paid volunteer time off.
• Generous paid parental leave and family planning support.
• Mental health, coaching benefits, and gender-affirming care.