Senior Machine Learning Engineer, Ads Foundational Representations

Stack

Responsibilities

• ▹Develop multimodal and content embeddings: embed organic (posts, comments, subreddits) and promoted (ads, products) content into a shared space
• ▹Establish contextual and behavioral relevance with Product & Data Science, fine-tuning embeddings and metrics
• ▹Build knowledge graph embeddings (e.g. brands) for high-precision targeting and business insights
• ▹Model user intent through batch & real-time sequence modeling, LLM summarization
• ▹Build LLM-based representations using LLMs, VLMs, and foundation models to improve ranking outcomes
• ▹Develop new or iterate on embedding models for advertising use cases, from aggregation pipelines to two-tower architectures and sequence models
• ▹Work with local and 3rd-party LLMs/VLMs: extract representations, develop evaluation methodology, prompt- and fine-tune models
• ▹Build data processing and inference pipelines for developed models
• ▹Qualitative and quantitative evaluation of features, from internal benchmarks to online experiments
• ▹Ensure reliability, scalability, and performance of ML systems through automated testing and monitoring
• ▹Participate in modeling and code reviews, providing feedback to teammates
• ▹Collaborate cross-functionally to translate business requirements into technical solutions

Requirements

• ▹5+ years of hands-on experience with the full lifecycle of designing, training, evaluating, testing, and deploying industry-level models
• ▹Experience building NLP or CV models and integrating them at scale
• ▹Experience developing complex features/embeddings for downstream models
• ▹Experience with mainstream DL frameworks: PyTorch or TensorFlow
• ▹Excitement about working with data and looking behind the metric numbers

Nice to have

• ▹Experience with the team's stack (Python, PyTorch, Airflow, BigQuery, Ray, Kubernetes, Kafka, GCP)
• ▹Familiarity with the Ads domain and/or search/recommender systems
• ▹Tech leadership experience: mentoring junior engineers, leading complex projects
• ▹Hands-on experience using, fine-tuning, or building LLMs

Soft skills

What we offer

• ▹Global benefit programs for workspace, professional development, and caregiving support
• ▹Family planning support
• ▹Gender-affirming care
• ▹Mental health & coaching benefits
• ▹Private pension plan with employer matching
• ▹100% employer-sponsored group medical plan
• ▹Income replacement programs
• ▹Flexible vacation & paid volunteer time off
• ▹Generous paid parental leave

About the company

Reddit is a community of communities where people share, discuss, and vote on the topics they care about. With 100,000+ active communities and approximately 126 million daily unique visitors, Reddit is one of the internet's largest sources of information. This role can be done remotely from the UK or the Netherlands.