Senior Machine Learning Engineer, Ads Foundational Representations

• Join the Ads Foundational Representations team, building signals and representations of Reddit's core entities — ads, posts, users — that capture the semantic, contextual and behavioural information Reddit Ads needs. • Build embeddings that make sense of organic and promoted content and that understand users' interests based on the content they engage with. • Own the full-cycle execution of ML projects, from collaborating on requirements and design through to feature implementation and experimentation. • Work across multimodal embeddings, contextual relevance, knowledge graph embeddings, user intent modeling and LLM-based representations. • Work fully remotely from anywhere in the UK or the Netherlands.

• Bring 5+ years of hands-on experience across the full lifecycle of designing, training, evaluating, testing and deploying industry-level models. • Build NLP or CV models and integrate them at scale. • Develop complex features and embeddings for downstream models. • Work confidently with mainstream deep learning frameworks such as PyTorch or TensorFlow. • Bring excitement about working with data and a readiness to look behind the metric numbers.

• Bring experience with the team's stack, including Python, PyTorch, Airflow, BigQuery, Ray, k8s, Kafka and GCP. • Bring familiarity with the Ads domain and/or Search and Recommender systems. • Bring tech leadership experience, mentoring junior engineers and leading complex projects. • Bring hands-on experience using, fine-tuning or building LLMs.

• Develop new or iterate on existing embedding models for advertising use cases, from aggregation pipelines to two-tower architectures and sequence models. • Work with local and 3rd-party LLMs and VLMs to extract representations, develop evaluation methodologies, and prompt tune and fine-tune large models. • Build data processing and inference pipelines for the models the team develops. • Run qualitative and quantitative evaluation end to end, from internal benchmarks to downstream offline metrics to online experiments. • Ensure the reliability, scalability and performance of ML systems through automated tests, monitoring and best practices for model management. • Participate in modeling and coding reviews and collaborate with cross-functional teams to translate business requirements into technical solutions.

• Join a flexible-first workforce working remotely from anywhere in the UK or the Netherlands. • Receive a Group Personal Pension Scheme with employer match, plus private medical and dental cover. • Take flexible vacation and paid volunteer time off, with generous paid parental leave. • Access family planning support, gender-affirming care, and mental health and coaching benefits. • Benefit from income replacement programs and a Bike to Work scheme.

Reddit is a community of communities, built on shared interests, passion and trust, and home to some of the most open and authentic conversations on the internet. With 100,000+ active communities and around 126 million daily active unique visitors, it is one of the internet's largest sources of information, where users submit, vote and comment on the topics they care most about.