Staff Machine Learning Engineer, Ranking and Personalization

📋 Description

• • **Why This Role Matters:** As a **Staff Machine Learning Engineer, Ranking and Personalization** at Reddit, you will play a pivotal role in shaping how millions of users discover and engage with interactive apps and games on one of the internet’s largest platforms. Reddit’s Developer Platform team is pioneering new ways for communities to connect, play, and collaborate, and your work will directly influence how these experiences are personalized and ranked for users. This is a high-impact, 0→1 opportunity where you’ll define the technical direction for ranking and personalization, ensuring that Reddit’s 126 million daily active users find the most relevant and engaging content tailored to their interests.
• • **Day-to-Day Responsibilities:**
• • **Design and Deploy Cutting-Edge ML Models:** You will lead the development of next-generation ranking and personalization models that power the discovery of Developer Platform apps and games across Reddit’s surfaces, including feeds, notifications, and cross-platform entry points. This involves leveraging advanced techniques like user/item embeddings, multi-task learning, and sequential modeling to optimize relevance and engagement.
• • **Collaborate Cross-Functionally:** Work closely with Product Managers, Data Scientists, Backend Engineers, and the Core Ranking/ML Platform teams to define signals, APIs, and feedback loops for building, deploying, and iterating on ranking models. Your role will bridge the gap between technical implementation and product outcomes, ensuring that models drive measurable impact on user engagement and retention.
• • **Innovate Retrieval and Experimentation:** Explore and productionize new approaches to retrieval, ranking, and experimentation that unlock novel experiences for Developer Platform. This includes designing performant, stable, and efficient ML systems capable of handling high-throughput decision-making, such as recommendation, ads, search, or feed ranking.
• • **Champion Model Quality and Best Practices:** Establish and uphold best practices for model quality, reproducibility, and experimentation. This includes implementing offline evaluation frameworks, A/B testing methodologies, and monitoring systems to detect model degradation or health issues. You’ll ensure that ranking systems are reliable, scalable, and aligned with Reddit’s long-term goals.
• • **Mentor and Lead Technical Discussions:** As a Staff-level engineer, you will mentor junior and mid-level engineers, fostering a culture of technical excellence and collaboration. You’ll lead technical discussions, shape the ranking and personalization strategy for Developer Platform, and advocate for engineering best practices such as testing, code reviews, and documentation.
• • **Own End-to-End Problem Solving:** Take ownership of problems from inception to deployment, including framing objectives, defining signals, training models, and analyzing experiment results. You’ll be responsible for turning noisy behavioral data into actionable insights and clear wins for users, creators, and developers, ensuring that your work directly moves core product metrics like engagement and daily active users (DAU).
• • **About Reddit and the Team:**
• • Reddit is a community of communities, built on shared interests, passion, and trust. With over 100,000 active communities and 126 million daily active unique visitors, Reddit is one of the internet’s largest sources of information and conversation. The Developer Platform team is at the forefront of this mission, empowering third-party developers, moderators, and everyday users to create innovative apps, games, and tools that redefine how communities interact on the platform.
• • The **Growth team** within Developer Platform focuses on helping users discover the right apps and games at the right time. This team is highly collaborative, cross-functional, and values impact, personal growth, openness, and kindness. You’ll work alongside engineers, PMs, designers, and data scientists who ship quickly while maintaining a high bar for reliability and performance across Reddit’s web, mobile, and backend stack.
• • **What You’ll Learn and Achieve:**
• • **Technical Growth:** You’ll have the opportunity to work on cutting-edge ranking and personalization systems, gaining hands-on experience with large-scale ML models, representation learning, and recommender systems. This role will deepen your expertise in modern ML techniques and their application in production environments, positioning you as a leader in the field.
• • **Leadership and Impact:** This is a career-defining role where you’ll set the technical direction for Developer Platform’s ranking strategy, mentor engineers, and influence how interactive experiences are discovered and engaged with by millions of users. Your work will directly shape the future of Reddit’s Developer Platform, leaving a lasting impact on the platform’s growth and user experience.