Principal Software Engineer, Build Platform

Roblox•San Mateo, CA

4d•$345,040 - $399,420•Onsite

About The Position

As a Principal Software Engineer on Roblox’s Build Platform team, you will set the technical direction for the infrastructure behind AI-powered creation on Roblox. Build enables people to make games by describing them, on mobile and in Studio. The team owns the platform underneath, including the cloud-hosted agent harness, tools and skills, and evaluation framework. You will be the senior technical leader shaping its architecture. The role spans the full agent stack: orchestrating long-running, multi-step workflows; integrating and routing models across providers; executing tools and skills; operating sandboxed game environments; scaling evaluations; and building the reliability, safety, and cost systems needed to serve millions of creators. You will own the platform’s technical architecture and long-term roadmap, define how agent quality is measured, and build evaluation infrastructure to inform model, prompt, and skill decisions. You will partner with product teams, ML infrastructure, and Safety, while providing hands-on technical leadership, mentorship, and design reviews.

Requirements

8+ years of experience building and operating large-scale distributed systems, including technical leadership across multiple teams.
Deep experience designing backend platforms used by other engineering teams.
Hands-on experience with production AI/ML systems, such as model serving, orchestration, LLM integration, or agentic execution loops involving planning, tool use, recovery, or long-running workflows.
Strong understanding of tool and skill design and structured evaluation for AI systems.
Sound judgment in weighing tradeoffs and making pragmatic decisions under ambiguity.
Bachelor of Science in Computer Science or a related field, or equivalent professional experience.
Clear communication skills, including the ability to explain complex technical direction to engineers, product teams, and leadership.
Interest in defining how AI agents create at scale while remaining hands-on.

Nice To Haves

Experience with workflow engines such as Temporal.
Experience with multi-provider model routing.
Experience with AI cost management.

Responsibilities

Own the technical architecture and long-term roadmap for the Build agent platform.
Design production AI workloads for reliability, safety, observability, and cost efficiency, including usage metering and model-routing strategy.
Define how agent quality is measured and build evaluation infrastructure to guide model, prompt, and skill decisions.
Partner with Build product teams, ML infrastructure, and Safety to ship capabilities quickly and safely.
Raise the engineering bar through design reviews, mentorship, and hands-on technical leadership.
Set technical direction for infrastructure supporting AI-powered creation on Roblox.