Senior Staff Machine Learning Engineer, ML Understanding
About this role
The user understanding team at Reddit builds a unified, high-fidelity representation of each user that powers personalization across the entire platform. The person in the Senior Staff Machine Learning Engineer role will set the technical direction for this space, leading the design and implementation of the core user representation layer which spans embeddings, interest modeling, and key user attributes. They will apply large language models and foundation models to evolve user modeling beyond traditional representations toward dynamic user profiles and semantic reasoning over user behavior.
This role exists to drive step-change improvements in fidelity, adaptability, and expressiveness for hundreds of millions of daily active users, ensuring the foundation is scalable, reliable, and adopted across feeds, search, notifications, and ads. An ideal candidate brings deep expertise in mainstream machine learning user modeling approaches, a proven track record of shipping ambiguous initiatives to production, and the ability to mentor senior and staff engineers while balancing latency, cost, and performance.
What you will do
- Define a unified user understanding framework and strategy detailing how user representations are computed, stored, and exposed.
- Lead the design and implementation of advanced large-scale user representation learning models shared across multiple platform surfaces.
- Evolve user modeling beyond traditional techniques by leveraging large language models for dynamic profiles and intent inference.
- Partner with platform and infrastructure teams to build scalable feature pipelines, storage solutions, and low-latency serving APIs.
- Collaborate with product teams across feeds, notifications, search, and ads to drive experimentation and measure end-to-end impact.
- Mentor senior to staff engineers, lead design reviews, and establish technical best practices across the domain.
What you need
- Ten or more years of experience building and scaling production-grade machine learning systems in user modeling or recommender systems.
- Demonstrated track record of guiding ambiguous, high-impact initiatives from initial concept through production deployment.
- Strong fundamentals in mainstream user understanding machine learning approaches such as representation learning and behavioral modeling.
- Experience applying large language models or foundation models to evolve existing systems beyond incremental improvements.
- Ability to think in systems by considering data, training, evaluation, serving, and adoption as a cohesive whole.
Benefits
- Comprehensive Healthcare Benefits and Income Replacement Programs
- 401k with Employer Match
- Family Planning Support and Gender-Affirming Care
- Mental Health & Coaching Benefits
- Flexible Vacation & Paid Volunteer Time Off
- Generous Paid Parental Leave
Skills and tech stack
Questions candidates ask
What is the remote policy for this role?
The position is remote within the United States.
What is the salary range for this position?
The base salary range is $266,000 to $372,400 USD. In addition to base salary, the role is eligible to receive equity in the form of restricted stock units.
What will I actually be working on?
You will lead Reddit's next-generation user understanding initiative by building a unified, high-fidelity representation of each user to power personalization across feeds, search, notifications, and ads. This includes leveraging large language models and foundation models for dynamic user profiles and intent inference.
What level of experience is required?
Candidates must have at least 10 years of experience building and scaling production-grade machine learning systems, particularly in user modeling, large-scale representation learning, or recommender systems.