Principal/Senior Machine Learning Scientist - Search and Discovery

With Roblox’s daily active users growing at a record pace, we are seeking experienced machine learning researchers who thrive on solving complex challenges and designing scalable, ground breaking solutions. In this role, you will innovate on LLMs, VLMs, autoregressive models, or other large models for user understanding, content understanding, recommendation, and agentic search. Your work will lay the foundation for personalizing user experiences, enhancing engagement and retention, and driving growth within the creator ecosystem.

In search and discovery, you will contribute to the core systems that enable users to discover and interact with experiences across Roblox. On Search, that work spans the end-to-end user search journey, covering query suggestions, autocomplete, and retrieval and ranking. These systems drive exploration and engagement across all surfaces, helping users find relevant and exciting content. Looking ahead, our team aims to innovate further by developing auto-generated summaries, images, and videos from experience content to improve discoverability and inspire user exploration.

Our mission is to connect a billion users with the best content and connections at the right time, tackling diverse challenges in advertising, search, and discovery at an unprecedented scale. Join us and play a pivotal role in shaping the future of Roblox’s search and discovery.

You Will:

• Design and implement the machine learning solutions that power agentic search and discovery systems to drive Roblox content distribution.
• Design and implement large scale recommendation models.
• In this role, you will innovate on LLMs, VLMs, autoregressive models, or other large models for query understanding, user understanding, content understanding, recommendation, and agentic search.
• Design eval and post-training loops - SFT, preference optimization, and RL - for ranking, query understanding, and agentic systems.
• Balance researching new technologies with a practical approach to integrate research efforts into the Roblox products.
• Collaborate with other teams within Roblox to make sure we are building products with a community first approach.
• Communicate with the industry and communities where applicable and be ambassador for Roblox.

You have:

• You have 7+ (for principal) or 4+ (for senior) years of experience designing and building scalable machine learning solutions. Experienced with transformer based model training, inference, and product integration. Break down product requirements into iterative deliverable stages.
• Depth in recommendation, search retrieval and ranking, or LLM post-training and agentic systems is a plus.
• You have a BS, MS, or PhD in Computer Science or a related discipline or equivalent experience.
• You have initiated and facilitated challenging technical decisions across multiple teams and organizations.
• While deeply technical, you always start with the needs of the user, whether they are Roblox users or internal engineers.
• A creative and strategic approach to solving hard problems. You simplify the complex. You bring in fresh ideas from new places.