Software Engineer - Sandbox Service

Pantera Capital; Greater London; On-site; GBP 80,000 - 100,000; Full time

Job summary

A technology-focused organization in Greater London is seeking a technically proficient engineer with expertise in Rust, C++, or Go. The role emphasizes deep technical work in a dynamic environment, supporting secure systems and enabling models to execute code. Ideal candidates will have experience in Linux or Windows systems, virtualization technologies, and solid networking knowledge. This position promises competitive benefits, including medical coverage and equity opportunities.

Benefits

Equity

Comprehensive medical coverage

Vision and dental coverage

401(k) retirement plan

Disability insurance

Life insurance

Various discounts and perks

Responsibilities

• Engage in deeply technical work within a fast-moving environment.
• Contribute to the development and maintenance of secure, scalable systems.
• Support critical workloads enabling models to run code and interact with tools.

Skills

Expert knowledge of Rust, C++ or Go

Familiarity with Python

Deep experience with Linux or Windows systems

Experience with virtualization and containerization technologies

Solid knowledge of the networking stack

Job description

About xAI

xAI’s mission is to create AI systems that can accurately understand the universe and aid humanity in its pursuit of knowledge. Our team is small, highly motivated, and focused on engineering excellence. This organization is for individuals who appreciate challenging themselves and thrive on curiosity. We operate with a flat organizational structure. All employees are expected to be hands‑on and to contribute directly to the company’s mission. Leadership is given to those who show initiative and consistently deliver excellence. Work ethic and strong prioritization skills are important. All engineers are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates.

About the team

The Sandbox service team at xAI 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.

About the role

Expect deeply technical work in a fast-moving environment. We prioritize speed and rapid iteration without compromising on reliability or performance. Ideal candidates have strong backgrounds in at least the following:

• Expert knowledge of Rust, C++ or Go
• Familiarity with Python
• Deep experience with either Linux or Windows systems (familiarity with both is a strong plus)
• Experience with virtualization and containerization technologies (e.g., cgroups, KVM, gVisor, QEMU)
• Solid knowledge of the networking stack

Interview process

After submitting your application, the team reviews your statement of exceptional work and CV. If your application passes this stage, you will be invited to a 15 minute interview (“phone interview”) during which a member of our team will ask some basic technical questions. If you clear the initial phone interview, you will enter the main process, which consists of at least two technical interviews:

1. Coding interview in Rust or C++.
2. Distributed systems design interview.

Benefits

Base salary is just one part of our total rewards package at xAI, which also includes equity, comprehensive medical, vision, and dental coverage, access to a 401(k) retirement plan, short & long-term disability insurance, life insurance, and various other discounts and perks.

xAI is an equal opportunity employer.