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Posted 10 mo agoFirst seen 23 d ago
Software Engineer, Sandbox Service
Posted by xAI on 18 December 2025, 318 days ago. Still on their Greenhouse board when we checked 33 min ago. Half of xAI's roles come down within 75 days.
What the posting is about
Develop and maintain secure, scalable sandbox service for AI models. Work on full stack, from cluster orchestration to node-level tuning. Enable real-time code execution and reinforcement learning. Expertise in Rust, C++, Go, Python, Linux, Windows, virtualization, and networking required.
Read out of the posting
Levelmid
Experience asked5+ years
EmploymentFull time
LocationLondon, England, United Kingdom
RemoteNot stated
Visa sponsorshipNot stated
SalaryNot published, and most postings do not
Posted2025-12-18
Found viagreenhouse, direct from their system
We saw it 10 months after it went up.
The posting, as the company wrote it
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.
SpaceXSI is an equal opportunity employer. For details on data processing, view our Recruitment Privacy Notice .
Copied from xAI’s own board, not rewritten.
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