Principal Machine Learning Engineer, Communication Safety

<div class="content-intro"><p><span style="font-weight: 400;">Every day, tens of millions of people come to Roblox to explore, create, play, learn, and connect with friends in 3D immersive digital experiences– all created by our global community of developers and creators.&nbsp;</span></p> <p><span style="font-weight: 400;">At Roblox, we’re building the tools and platform that empower our community to bring any experience that they can imagine to life. Our vision is to reimagine the way people come together, from anywhere in the world, and on any device.</span><strong> </strong><span style="font-weight: 400;">We’re on a mission to connect a billion people with optimism and civility, and looking for amazing talent to help us get there.&nbsp;</span></p> <p><span style="font-weight: 400;">A career at Roblox means you’ll be working to shape the future of human interaction, solving unique technical challenges at scale, and helping to create safer, more civil shared experiences for everyone.</span></p></div><h2><strong>Why Safety?</strong></h2> <p>At Roblox, we strive to connect a billion people with optimism and civility, and the Safety organization’s mission is to become the leader in civil immersive online communities. We systematically and proactively detect, remove, and prevent problematic content and behavior. In doing so, we keep Roblox safe, civil, and inclusive, fostering positive relationships between people around the world.</p> <h2><strong>Why Safety AI Systems?</strong></h2> <p>As a <strong>Senior/Principal Machine Learning Engineer</strong> for Safety AI Systems, you will define the future of proactive moderation, driving immense social impact through cutting-edge, innovative ML solutions. This role is a fusion of a Principal Engineer's technical authority and an Engineering Manager's leadership, focused on the most critical and ambiguous safety challenges.</p> <p>You will set the <strong>3-5 year technical strategy and architectural blueprint</strong> for how Roblox uses machine learning—from high-velocity text filtering to leveraging multimodal Generative AI—to combat the most complex critical harms on the platform. <strong>You will own the execution roadmap and technical planning, directly guiding the launch of high-priority new ML projects.</strong> You will be responsible for defining the standards of innovation in data quality, model robustness, and ethical deployment across the entire Content &amp; Communication Safety ML pillar.</p> <p>You will lead and scale a high-performing group of individual contributors, providing both strategic oversight and hands-on guidance to the teams responsible for the architectural development of massive-scale systems that mitigate abuse and harassment before it impacts our community.</p> <p>You will feel a deep sense of responsibility in proactively protecting our community—thoughtfully and fairly—while balancing user freedom with platform civility. Your efforts will ensure Roblox remains one of the safest places on the internet for users.</p> <h2><strong>You will:</strong></h2> <ul> <li><strong>Define and Own the Technical Vision:</strong> Define and lead the <strong>multi-year technical vision, architectural strategy, and execution</strong> for machine learning solutions across Content and Communication Safety, ensuring these systems proactively and effectively detect and prevent high-severity, critical harms at massive scale.</li> <li><strong>Provide Senior/Principal-Level Architecture:</strong> Act as the <strong>highest technical authority</strong> for the Content Safety ML domain, guiding the architecture and long-term maintainability of foundational models, data pipelines, and real-time inference services.</li> <li><strong>Drive Cross-Org Alignment:</strong> Identify and champion the most ambiguous, high-leverage technical problems, driving alignment and securing investment for <strong>organization-wide ML infrastructure</strong> and platform development initiatives that benefit all of Trust &amp; Safety.</li> <li><strong>Lead Innovation in Safety:</strong> Oversee the adoption and safe deployment of innovative technologies (e.g., advanced NLP, self-supervised learning, multimodal LLMs) to anticipate and mitigate novel abuse vectors, moving beyond reactive detection to <strong>proactive intervention</strong>.</li> <li><strong>Strategic Stakeholder Partnership:</strong> Collaborate with executive-level Product, Data Science, Policy, and Operations leaders to define and prioritize the strategic machine learning roadmap, influencing product strategy and demonstrating the impact of ML on user trust and safety outcomes.</li> </ul> <h2><strong>You have:</strong></h2> <ul> <li><strong>8+ years</strong> of experience designing, developing, and operating large-scale, high-impact machine learning systems in a production environment.</li> <li><strong>5+ years</strong> of experience in technical leadership, management, or mentorship roles, ideally having managed Engineering Managers or Senior/Principal-level individual contributors.</li> <li>A proven track record of successfully setting the <strong>long-term technical direction</strong> for an entire ML domain or pillar, demonstrating the ability to take ambiguous problems from concept to scaled production impact.</li> <li>Deep expertise in advanced ML architectures, including <strong>Large Language Models (LLMs)</strong>, transfer learning, or other foundation model technologies, especially applied to text or multimodal data.</li> <li>Expertise in architecting scalable, real-time ML inference services and robust data pipelines operating at millions of requests per second.</li> <li>Demonstrated success in leading and resolving high-stakes, cross-functional conflicts and technical disagreements, with an ability to build consensus among diverse stakeholders.</li> <li>Exceptional product sense and strategic planning ability: able to translate platform safety requirements into an achievable, iterative technical roadmap.</li> </ul> <h2><strong>You are:</strong></h2> <ul> <li><strong>A Visionary Architect:</strong> Capable of synthesizing complex business and safety goals into a clear, compelling, and actionable technical strategy.</li> <li><strong>An Inspiring Leader:</strong> Passionate about developing the next generation of technical leaders, managers, and engineers.</li> <li><strong>Comfortable with Ambiguity:</strong> You thrive in undefined or open-ended problem spaces, providing structure, clarity, and decisive direction to your teams.</li> <li><strong>An Executive Communicator:</strong> Highly effective at communicating complex technical concepts to both engineering teams and non-technical executive leadership.</li> <li><strong>Committed to Ethical AI:</strong> Dedicated to building ML systems that are fair, transparent, and operate with the utmost responsibility toward user safety and platform civility.</li> </ul><div class="content-pay-transparency"><div class="pay-input"><div class="description"><p>For roles that are based at our headquarters in San Mateo, CA: The starting base pay for this position is as shown below. The actual base pay is dependent upon a variety of job-related factors such as professional background, training, work experience, location, business needs and market demand. Therefore, in some circumstances, the actual salary could fall outside of this expected range. This pay range is subject to change and may be modified in the future. All full-time employees are also eligible for equity compensation and for benefits as described on <strong><a href="https://careers.roblox.com/total-rewards">this page</a></strong>.</p></div><div class="title">Annual Salary Range</div><div class="pay-range"><span>$293,800</span><span class="divider">&mdash;</span><span>$343,340 USD</span></div></div></div><div class="content-conclusion"><p>Roles that are based in an office are onsite Tuesday, Wednesday, and Thursday, with optional presence on Monday and Friday (unless otherwise noted).</p> <p>Roblox provides equal employment opportunities to all employees and applicants for employment and prohibits discrimination and harassment of any type without regard to race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state or local laws. Roblox also provides reasonable accommodations to candidates with qualifying disabilities or religious beliefs during the recruiting process.</p> <p>For US based roles only, please note the Company may not be able to employ candidates for this role who have United States work authorization related to certain U.S. visa categories, or support future H-1B sponsorship at this time.</p></div>