Principal Software Engineer Jobs in San Mateo, CA

Why Safety?

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 detect, remove, and prevent problematic content and behavior, and we make Roblox accounts secure and free from compromise. We cover a broad area of the tech spectrum, including machine learning, classifiers for 3D models, experimentation, automation, detection workflows, and AI-powered text filters. Aligned and partnering with product teams, we use this toolbelt to discover new opportunities, influence and shape the product roadmap and prioritization, build safety products, and measure the impact on our community of users and developers. In doing so, we keep Roblox safe, civil, and inclusive, and we foster positive relationships between people around the world.

Why Safety Foundation?

Safety Foundation is the infrastructure backbone that powers safety across Roblox. Every piece of content reviewed, every moderation action taken, every safety workflow running anywhere on the platform flows through systems built by this team. We are the platform that other safety teams build on — and right now, we're in the middle of one of the most significant evolutions in our history.

We're scaling to handle 10x more traffic while keeping cost growth in check. We're rebuilding the platform to be AI-first, natively supporting agentic and ML-driven safety workflows without compromising on security or auditability. And we're radically improving developer velocity — cutting the time it takes any team to integrate safety capabilities from months to hours.

As a Principal Software Engineer on Safety Foundation, you'll be the hands-on tech lead for a group of engineers on the team. You'll set technical direction, own architecture decisions, and stay deeply engaged in the work. Your decisions will shape how safety works across all of Roblox — for over 100+ daily monthly active users.

You Will:

• Serve as the hands-on tech lead for a group of engineers on the Safety Foundation team — setting technical direction, driving execution, and staying close to the code
• Lead the design and implementation of a scalable, cost-efficient platform engineered for 10x traffic growth
• Drive the AI-first transformation of the safety platform: architecting agentic and ML-integrated workflows with the security, auditability, and reliability that production safety systems require
• Build the developer experience layer that enables product teams across Roblox to integrate safety capabilities in hours, not months
• Partner closely with Trust & Safety ML, User Safety, Safety Operations, and product teams to translate platform needs into durable infrastructure
• Define backend standards and patterns across the team; raise the technical bar through code review, architecture guidance, and mentorship
• Identify and resolve performance bottlenecks across networking, data, and compute — at scale

You Have:

• 8+ years of experience building large-scale backend/distributed systems and shipping high-quality systems to production. Strong preference for candidates who have experience with building developer platforms.
• 4+ years acting as a tech lead: setting direction, driving execution, and growing engineers at multiple levels
• Deep proficiency in Go or a similar compiled language (Go strongly preferred). Experience with CQRS & Event Sourcing is a plus
• Experience with NoSQL databases at scale (DynamoDB, Cassandra, or similar)
• Experience with or strong interest in AI/ML platform integration — pipelines, agentic workflows, HITL workflows or similar
• BA/BS in Computer Science, Engineering, or a related technical field — or equivalent experience

You Are:

• A hands-on technical leader. You can zoom out to own the architecture and zoom in to write the hard code. You don't choose between leading and building — you do both.
• A platform thinker. You design for reuse, velocity, and reliability. You understand that your customers are other engineering teams, and you build with them in mind.
• Comfortable with ambiguity. You thrive on open-ended, gnarly problems. You can break them down, build alignment, and drive them to resolution — without waiting for perfect requirements.
• A team-player & multiplier. You are collaborative & strive to make everyone around you better — through rigorous code & architecture reviews, clear technical communication, and a genuine investment in the growth of the people you work with.