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.
We are building one of the world’s largest AI supercomputers from the ground up. As part of the Compute Infrastructure team, you will own both the raw GPU supercomputer and the platform layer that runs on top of it. You will work across the full stack — from low-level GPU kernel optimizations and Linux kernel internals to massive-scale orchestration and virtualization — to make training and inference at SpaceXSI as fast, reliable, and scalable as possible.
This is a broad, high-impact role that combines hardcore supercompute and compute infrastructure work. Your contributions will directly accelerate Grok’s training speed and overall AI progress.
- Design, build, and optimize massive GPU clusters for extreme-scale training and inference workloads
- Develop and tune low-level CUDA kernels (GeMM, Attention, etc.), using CUTLASS, Tensor Cores, and Nsight for maximum performance
- Profile, debug, and eliminate bottlenecks across GPU memory hierarchy, networking fabric, filesystems, and multi-GPU operation
- Collaborate closely with AI research teams to deliver production-grade performance and scalability
- 5+ years of experience with low-level system programming in C/C++
- Deep low-level systems programming (C/C++/PTX/SASS)
- Strong experience with large-scale GPU clusters or distributed compute infrastructure at production scale
- Hands-on work with GPU kernel optimization (CUTLASS, custom kernels, Nsight profiling)
- Track record of building or running high-performance infrastructure for AI workloads (training or inference platforms)
- Ability to reason from first principles and optimize for both memory-bound and compute-bound scenarios
$200,000 - $375,000 USD
Base salary is just one part of our total rewards package at SpaceXSI, 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.
SpaceXSI is an equal opportunity employer. For details on data processing, view our Recruitment Privacy Notice.
Skills Required
- 5+ years of experience with low-level system programming in C/C++
- Deep low-level systems programming experience with C/C++, PTX, or SASS
- Experience with large-scale GPU clusters or distributed compute infrastructure at production scale
- Hands-on experience with GPU kernel optimization, including CUTLASS, custom kernels, and Nsight profiling
- Experience building or operating high-performance infrastructure for AI training or inference workloads
- Ability to optimize memory-bound and compute-bound workloads from first principles
xAI Compensation & Benefits Highlights
The following summarizes recurring compensation and benefits themes identified from responses generated by popular LLMs to common candidate questions about xAI and has not been reviewed or approved by xAI.
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Healthcare Strength — Healthcare is described as comprehensive, including medical, dental, vision, mental health support, and fertility benefits. Additional protections such as disability and life insurance, plus HSA/FSA options, are also outlined.
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Equity Value & Accessibility — Equity is positioned as a core component of total rewards alongside high base salaries for technical roles. Pre‑IPO stock grants are highlighted as enabling participation in potential company growth.
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Leave & Time Off Breadth — The package includes flexible or generous PTO, paid holidays, and paid sick days. Company materials also describe flexible vacation policies intended to help manage fast‑paced workloads.
xAI Insights
What We Do
Understand the Universe
