Software Engineer, Sandbox Service

X.ai; Greater London; On-site; GBP 107,000 - 262,000; Full time

Benefits offered by this job

Equity

Healthcare

Dental coverage

Cash plan

Income protection

Life insurance

Discounts

Job summary

SpaceXSI is seeking a Software Engineer for the Sandbox Service. You will help build a secure, scalable environment that lets models run code, build software, interact with tools, and control applications with user interfaces in remote environments.

The role spans containers and virtual machines on large clusters, from job orchestration to filesystem performance tuning. Required: experience with Rust, C++, or Go, and virtualization/containerization; preferred: Python and networking knowledge.

Qualifications

• Experience with Rust, C++, or Go.
• Experience with virtualization and containerization technologies (e.g., cgroups, KVM, gVisor, QEMU).

Responsibilities

• Maintain a secure, scalable sandbox service enabling models to run code and interact with tools in remote environments.
• Support reinforcement learning workflows and real-time testing in control of applications and interfaces.

Skills

Rust, C++, or Go

Tools

Virtualisation

Containerisation

Job description

SpaceX was founded under the belief that a future where humanity is out exploring the stars is fundamentally more exciting than one where we are not. Today, SpaceX is actively developing the technologies to make this possible, with the ultimate goal of making life multiplanetary and expanding consciousness to the stars. SpaceXSI is building Super Intelligence to help humanity understand the universe. Our teams are building the full Super Intelligence stack: from our Colossus supercomputers, to Grok models, to our suite of applications, including Grok Bot, Grok Build, Grok Imagine, Grok Voice, and X. We're creating a powerful flywheel where more compute trains better models, better models power more useful products, and what we learn from people using those products shapes what we build next.

SOFTWARE ENGINEER, SANDBOX SERVICE

The Sandbox service team at SpaceXSI builds and maintains a secure, scalable system that gives our models safe, controlled access to computational environments. This infrastructure powers critical workloads across training and product, enabling models to run code, build software, interact with tools, and even control applications with user interfaces. We provision containers and virtual machines on large-scale clusters, granting models interactive control over these remote environments. Our work spans the full stack: from orchestrating massive jobs and resource scheduling at the cluster level, to fine-tuning filesystem performance on nodes. The Sandbox service enables Grok to safely run and test code in real-time for user queries, and supports reinforcement learning in training, where models interactively explore tools ranging from compilers to productivity apps.

BASIC QUALIFICATIONS:

• Experience with Rust, C++, or Go
• Experience with virtualisation and containerisation technologies (e.g., cgroups, KVM, gVisor, QEMU)

PREFERRED SKILLS AND EXPERIENCE:

• Solid knowledge of the networking stack
• Familiarity with Python
• Deep experience with either Linux or Windows systems (familiarity with both is a strong plus)

COMPENSATION AND BENEFITS:

• £107,000 - £262,000 GBP
• Base salary is just one part of our total rewards package at SpaceXSI, which also includes equity, comprehensive healthcare and dental coverage, cash plan, income protection, life insurance, and various other discounts and perks.

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