Principal Software Engineer, Core Services

Overview

Principal Software Engineer on the Core Services team, building and evolving the foundational C#/.NET and Rust frameworks, shared libraries, and runtime integrations behind Roblox's global platform.

What you'll do

• Build and evolve shared C#/.NET and Rust frameworks, libraries, and SDKs, including HTTP/gRPC infrastructure, caching, configuration, and observability.
• Investigate performance from application code through the runtime: allocation pressure, garbage collection, lock contention, asynchronous execution, serialization, and network overhead.
• Design safe, efficient managed/native interoperability with explicit ownership, error handling, cancellation, and compatibility contracts.
• Create stable, usable APIs and lead their evolution across teams, balancing extensibility, performance, operational safety, and maintenance cost.
• Build automation for framework upgrades and service migrations, including AI-assisted workflows supported by compatibility tests, benchmarks, traffic replay, and canary evidence.
• Partner with deployment and service teams to make library changes easier to adopt, detect regressions early, and support safe rollout and rollback.
• Lead ambiguous technical initiatives, mentor engineers, and measure outcomes in reliability, resource efficiency, adoption, and developer productivity.

What you'll need

• Deep production experience in C#/.NET or Rust, with the ability and interest to work effectively across both ecosystems.
• Experience building and evolving reusable libraries, SDKs, frameworks, or runtime infrastructure adopted by multiple teams.
• Strong fundamentals in concurrency, asynchronous programming, memory management, networking, and distributed systems.
• A track record of diagnosing complex production problems and delivering measurable performance or reliability improvements.
• Experience designing stable APIs and managing compatibility, versioning, dependencies, and adoption across dependent systems.
• Demonstrated technical leadership: framing ambiguous problems, explaining tradeoffs, aligning stakeholders, mentoring engineers, and driving cross-team execution.
• A bachelor's degree in Computer Science or a related field, or equivalent experience.

Nice to have

• .NET runtime internals, GC and allocation optimization, thread-pool behavior, or production profiling.
• Rust ownership and lifetimes, async runtimes, concurrent data structures, or performance-sensitive library design.
• Managed/native interoperability, FFI, native memory diagnostics, or cross-platform packaging.
• Contract-driven code generation, serialization, compatibility testing, or large-scale framework migrations.
• Automated validation and rollout of shared dependencies across a service fleet.

Details

• Based at Roblox headquarters in San Mateo, CA; onsite Tuesday, Wednesday, and Thursday, with optional presence on Monday and Friday.
• Annual base salary range $345,040 – $399,420 USD, plus equity compensation and benefits for full-time employees.
• For US-based roles only: the Company may not be able to employ candidates who have United States work authorization related to certain U.S. visa categories, or support future H-1B sponsorship at this time.