Senior Machine Learning Infrastructure Engineer, Embedding Platform

The LS Embedding Machine Learning Platform team is at the forefront of building highly expressive, machine learning models that power Reddit’s recommendation systems. We go beyond standard retrieval and ranking architectures, leveraging modern deep learning approaches and scalable model designs to enhance personalization across Reddit’s ecosystem. Our work impacts content discovery, user engagement, and platform growth at a massive scale.

As a Senior Machine Learning Infrastructure Engineer, you will work across both model development and ML platform to build large-scale learning systems that improve recommendation and personalization on Reddit. At the senior level, you will own major technical components end to end: designing models, implementing training and evaluation pipelines, and driving production deployment in close partnership with ML platform, product, and cross-functional ML teams.

• →Design, train, and improve large-scale machine learning platforms for recommendation or personalization systems.
• →Own and deliver major ML systems components end to end, from problem framing through production rollout.
• →Build and optimize end-to-end ML pipelines spanning data preparation, feature generation, training, evaluation, and deployment.
• →Improve distributed training, model efficiency, and online inference performance.
• →Apply modern modeling approaches including sequence modeling and related foundation-model techniques to Reddit use cases.
• →Develop reliable serving and monitoring patterns for low-latency, high-throughput production ML systems.
• →Work with cross-functional partners across product, relevance, ads, and core ML teams to deliver measurable improvements in user experience and business impact.
• →Drive rigorous offline and online evaluation, including experimentation, model diagnostics, and feedback-loop improvement.
• →Contribute to engineering quality through strong code, design reviews, documentation, and operational excellence.

• 5+ years of experience in machine learning engineering, with a strong focus on large-scale ML infrastructure and recommendation or personalization systems.
• Expertise in modern deep learning architectures, including sequence models and foundational models.
• Experience building or scaling ML platform for large datasets and high-traffic production environments.
• Demonstrated ability to independently scope and execute ambiguous technical work, while owning high-quality implementation details.
• Solid understanding of distributed training and inference concepts, such as data parallelism, model parallelism, pipeline parallelism, or related optimization techniques.
• Proficiency in Python and experience with modern ML frameworks such as PyTorch, TensorFlow, or similar.
• Strong software engineering fundamentals, including system design, debugging, testing, and performance optimization.
• Experience with A/B testing, model evaluation frameworks, and real-time feedback loops in large-scale production systems.
• Excellent communication skills, with the ability to effectively present complex ML concepts to technical and non-technical stakeholders.

This job posting may span more than one career level.

In addition to base salary, this job is eligible to receive equity in the form of restricted stock units, and depending on the position offered, it may also be eligible to receive a commission. Additionally, Reddit offers a wide range of benefits to U.S.-based employees, including medical, dental, and vision insurance, 401(k) program with employer match, generous time off for vacation, and parental leave. To learn more, please visit https://www.redditinc.com/careers/.

To provide greater transparency to candidates, we share base salary ranges for all US-based job postings regardless of state. We set standard base pay ranges for all roles based on function, level, and country location, benchmarked against similar stage growth companies. Final offer amounts are determined by multiple factors including, skills, depth of work experience and relevant licenses/credentials, and may vary from the amounts listed below.