Software Engineer, Sandboxing

United States Digital Space LLC; San Francisco (CA); On-site; USD 320,000 - 485,000; Full time

Job summary

United States Digital Space LLC seeks a senior systems engineer to design, build, and operate sandboxing infrastructure for untrusted code and agent workloads at scale. You will optimize startup time, isolation, and performance across kernel, hypervisor, and container runtimes, collaborating with research, product, and security teams.

You will work with cloud providers on hardware features and contribute to standardizing technical practices while mentoring others and sharing knowledge on Linux

Qualifications

• Linux systems programming or kernel development experience.
• Proficient in at least one systems language (Rust/C/C++/Go).
• Knowledge of virtualization/container isolation tech (KVM/QEMU/Firecracker/gVisor/runc).
• Understanding Linux namespaces, cgroups, scheduling, memory management.
• Experience profiling and debugging system-level performance.

Responsibilities

• Design, build, and operate sandboxing infrastructure for untrusted code and agent workloads at scale.
• Improve sandbox startup time, density, and throughput with snapshot/restore and warm pools.
• Strengthen isolation across compute, filesystem, and network with per-session credentials.
• Investigate and fix performance, reliability, and security issues at kernel, hypervisor, and container runtime levels.
• Build monitoring, tracing, and debugging tools to attribute latency and resource use inside sandboxes.
• Collaborate with researchers, product, and security teams to enable safe, fast sandboxing.

Skills

Linux systems programming

Rust

C/C++

Kernel debugging

Performance optimization

Strong communication

Security mindset

Team collaboration

Education

Bachelor's degree

Tools

KVM

QEMU

Firecracker

gVisor

runc

Job description

About the company

the company’s mission is to create reliable, interpretable, and steerable AI systems. We want AI to be safe and beneficial for our users and for society as a whole. Our team is a quickly growing group of committed researchers, engineers, policy experts, and business leaders working together to build beneficial AI systems.

About the role

Every time Claude runs code, uses a computer, or works as an agent, it does so inside a sandbox. Our Sandboxing team builds the isolation layer behind that work. The same systems run the code Claude writes for users, the environments we train and evaluate models in, and the agents our customers deploy.

These workloads are untrusted by design, and there are a lot of them. Sandboxes need to start in milliseconds, hold up under adversarial code, and scale to a very large number of concurrent sessions. You will work at the boundary between the Linux kernel, virtualization, and the container ecosystem. You will partner with research, product, and security teams to make sure that safe and fast do not trade off against each other.

Key responsibilities

• Design, build, and operate the sandboxing infrastructure that runs untrusted, model-generated code and agent workloads at scale
• Improve sandbox startup time, density, and throughput, including snapshot and restore, checkpointing, and warm pools
• Strengthen isolation across compute, filesystem, and network, including egress controls and per-session credential handling
• Investigate and fix performance, reliability, and security issues at the kernel, hypervisor, and container runtime level
• Build the monitoring, tracing, and debugging tools that show where time and resources go inside a sandbox
• Work with researchers to support reinforcement learning environments and evaluations that need fast, reproducible, isolated execution
• Work with product and platform engineers to expose sandboxes as a dependable, well-designed capability for Claude products and customers
• Partner with security teams to threat-model the platform and to test, harden, and respond to escape and abuse scenarios
• Work with cloud providers on the hardware and platform features that our workloads depend on
• Share knowledge on systems programming and Linux internals, and help set technical standards for the team

Minimum qualifications

• Software engineering experience in Linux systems programming, kernel development, or another low-level area
• Strong programming skills in at least one systems language such as Rust, C, C++, or Go
• Working knowledge of virtualization or container isolation technologies such as KVM, QEMU, Firecracker, gVisor, or runc
• Understanding of Linux resource management, including namespaces, cgroups, scheduling, and memory management
• Experience profiling and debugging performance issues at the system level
• Ability to work in unfamiliar codebases and technical areas, and to ship practical solutions with measurable results
• Strong communication skills and a commitment to building safe, reliable systems

Preferred qualifications

• Experience building or operating a multi‑tenant sandbox, serverless, or code execution platform
• Experience with microVMs, user‑space kernels, or lightweight virtualization, including snapshot and restore
• Experience with OS‑level security hardening, including seccomp, LSMs, and threat modeling of untrusted code
• Experience with eBPF and kernel tracing tools
• Experience with Kubernetes and cloud infrastructure at scale (AWS, GCP)
• Experience with network isolation, high‑performance networking, or building egress proxies and policy layers
• Experience with sandboxes for AI agents, computer use, or reinforcement learning environments
• Experience with GPU virtualization, accelerators, or performance work on machine learning workloads
• Prior experience as a technical lead or mentor

Representative projects

• Cutting sandbox cold start from seconds to milliseconds with snapshot‑based restore and pre‑warmed pools
• Designing a network egress policy layer so agents can reach approved services without exposing secrets
• Running many thousands of parallel reinforcement learning environments with strong isolation between them
• Building tracing tools that attribute latency and resource use inside a running sandbox
• Reducing per‑sandbox memory overhead to raise density on each host
• Hardening the runtime against escape attempts found in internal red‑team exercises

The annual compensation range for this role is listed below.

For sales roles, the range provided is the role’s On Target Earnings ("OTE") range, meaning that the range includes both the sales commissions/sales bonuses target and annual base salary for the role.

Annual Salary:

$320,000—$485,000 USD

LogisticsMinimum education: Bachelor’s degree or an equivalent combination of education, training, and/or experience Required field of study: A field relevant to the role as demonstrated through coursework, training, or professional experience Minimum years of experience: Years of experience required will correlate with the internal job level requirements for the position Location-based hybrid policy: Currently, we expect all staff to be in one of our offices at least 25% of the time. However, some roles may require more time in our offices. Visa sponsorship:We do sponsor visas! However, we aren't able to successfully sponsor visas for every role and every candidate. But if we make you an offer, we will make every reasonable effort to get you a visa, and we retain an immigration lawyer to help with this.

We think AI systems like the ones we're building have enormous social and ethical implications. We think this makes representation even more important, and we strive to include a range of diverse perspectives on our team.