Software Engineer - Kernels/CUDA (C++)

🏢 Summary: Role focused on building and optimizing large-scale GPU supercomputing infrastructure for AI training and inference. The position involves low-level GPU kernel optimization, distributed compute systems, and full-stack performance tuning across hardware and platform layers. Candidates will work closely with AI research teams to improve scalability, reliability, and training speed. 🗂️ Requirements: Deep low-level systems programming experience, Experience with large-scale GPU clusters, Hands-on GPU kernel optimization, Experience with distributed compute infrastructure, Ability to optimize memory-bound and compute-bound workloads, Strong communication skills 📃 Skills: CUDA, C, C++, PTX, SASS, CUTLASS, Nsight, Linux, GPU, Tensor 🏢 Description: SpaceXAI'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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: 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 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. RESPONSIBILITIES: - 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 PREFERRED SKILLS AND EXPERIENCE: - 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 COMPENSATION AND BENEFITS: - $180,000 - $440,000 USD - Equity - Medical, vision, and dental coverage - 401(k) retirement plan - Short and long-term disability insurance - Life insurance - Additional discounts and perks SpaceXAI is an equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.

🏢 Summary: High-impact compute infrastructure role focused on building and optimizing massive GPU supercomputers for AI training and inference. The position involves low-level systems programming, GPU kernel optimization, Linux kernel internals, orchestration, and distributed infrastructure to improve scalability, reliability, and performance of AI workloads. 🗂️ Requirements: Deep systems programming experience in C/C++ or Rust, Experience with large-scale GPU clusters or distributed compute infrastructure, Hands-on GPU kernel optimization using CUTLASS, custom kernels, or Nsight, Knowledge of Linux kernel internals, scheduling, virtualization, or orchestration, Experience building high-performance AI training or inference infrastructure, Ability to optimize memory-bound and compute-bound workloads, Experience operating exabyte-scale storage systems 📃 Skills: CUDA, CUTLASS, Tensor, Nsight, Linux, KVM, Firecracker, Kubernetes, C++, Rust 🏢 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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: 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 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 training speed and overall AI progress. RESPONSIBILITIES: - 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 - Work on Linux kernel internals, scheduling, memory management, and resource isolation at cluster scale - Build custom container orchestration, virtualization layers (KVM, Firecracker, etc.), and distributed systems that go beyond standard Kubernetes - Profile, debug, and eliminate bottlenecks across GPU memory hierarchy, networking fabric, filesystems, and multi-GPU operations - Create and maintain infrastructure-as-code, automation, and tools that keep the entire supercomputer reliable and efficient - Collaborate closely with AI research teams to deliver production-grade performance and scalability PREFERRED SKILLS AND EXPERIENCE: - Deep low-level systems programming (C/C++ or Rust) - Experience building and operating high performance exabyte scale storage systems - 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) - Experience with Linux kernel internals, scheduling, virtualization, or large-scale orchestration - 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 COMPENSATION AND BENEFITS: - $180,000 - $440,000 USD - Equity package - Medical, vision, and dental coverage - 401(k) retirement plan - Short and long-term disability insurance - Life insurance - Additional discounts and perks xAI is an equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.

🏢 Summary: High-impact compute infrastructure role focused on building and optimizing one of the world’s largest AI supercomputers for large-scale training and inference workloads. The position involves low-level GPU optimization, Linux kernel and virtualization work, distributed systems, and orchestration across massive GPU clusters. Engineers will collaborate closely with AI research teams to maximize performance, scalability, and reliability. 🗂️ Requirements: Deep systems programming experience in C/C++ or Rust, Experience with large-scale GPU clusters or distributed compute infrastructure, Hands-on GPU kernel optimization experience, Knowledge of Linux kernel internals, scheduling, virtualization, or orchestration, Experience building high-performance AI infrastructure for training or inference, Ability to optimize memory-bound and compute-bound workloads, Experience with exabyte-scale storage systems 📃 Skills: CUDA, CUTLASS, Tensor, Nsight, Linux, KVM, Firecracker, Kubernetes, C++, Rust, GPU, CUDA, GeMM, Attention 🏢 Description: ABOUT THE ROLE: 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 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 training speed and overall AI progress. RESPONSIBILITIES: - 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 - Work on Linux kernel internals, scheduling, memory management, and resource isolation at cluster scale - Build custom container orchestration, virtualization layers (KVM, Firecracker, etc.), and distributed systems that go beyond standard Kubernetes - Profile, debug, and eliminate bottlenecks across GPU memory hierarchy, networking fabric, filesystems, and multi-GPU operations - Create and maintain infrastructure-as-code, automation, and tools that keep the entire supercomputer reliable and efficient - Collaborate closely with AI research teams to deliver production-grade performance and scalability PREFERRED SKILLS AND EXPERIENCE: - Deep low-level systems programming (C/C++ or Rust) - Experience building and operating high performance exabyte scale storage systems - 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) - Experience with Linux kernel internals, scheduling, virtualization, or large-scale orchestration - 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 COMPENSATION AND BENEFITS: - $180,000 - $440,000 USD - Base salary plus equity - Medical, vision, and dental coverage - 401(k) retirement plan - Short and long-term disability insurance - Life insurance - Additional discounts and perks xAI is an equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.

🏢 Summary: High-impact engineering role focused on building and optimizing large-scale AI inference systems for serving Grok at massive scale. The position involves distributed infrastructure, GPU-level optimization, inference acceleration, and reliability engineering for high-concurrency production environments. Candidates will work end-to-end on scalable model serving, CI/CD infrastructure, and next-generation inference optimization. 🗂️ Requirements: Deep low-level systems programming in C/C++ or Rust, Experience with large-scale high-concurrency production serving, Experience with GPU inference engines, Strong background in batching, caching, load balancing, and parallelism, Experience with GPU kernels and code generation, Knowledge of quantization, speculative decoding, distillation, and low-precision numerics, Experience with testing, benchmarking, and reliability of inference services, Experience designing and implementing CI/CD infrastructure for inference 📃 Skills: C++, Rust, vLLM, SGLang, Triton, TensorRT-LLM, GPU, CI/CD, Quantization, Distillation, Caching, Batching, Parallelism, Load-balancing, Autoscaling 🏢 Description: SpaceXAI'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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. About the Role: We are building the high-performance inference platform that serves Grok to millions of users every day with lightning speed and perfect reliability. As a Member of Technical Staff - Inference, you will design and optimize large-scale model serving systems end-to-end. You will own everything from distributed infrastructure (global KV cache, continuous batching, load balancing, auto-scaling) to deep low-level optimizations (GPU kernels, quantization, speculative decoding, tail latency). This is a high-impact role where your work directly determines how fast and reliably users interact with Grok at massive scale. Responsibilities: - Architect and implement scalable distributed infrastructure for model serving (load balancing, auto-scaling, batch scheduling, global KV cache). - Optimize latency and throughput of model inference under real production workloads. - Build reliable, high-concurrency serving systems that serve billions of users with 100% uptime, 0% error rate, and excellent tail latency. - Benchmark, fine-tune, and accelerate inference engines (including low-level GPU kernel work and code generation). - Develop custom tools to trace, replay, and fix issues across the full stack — from orchestration down to GPU kernels. - Create robust CI/CD infrastructure for seamless endpoint deployment, image publishing, and inference engine updates. - Accelerate research on scaling test-time compute, RL rollout, and model-hardware co-design for next-generation systems. Basic Qualifications: - Deep low-level systems programming (C/C++ or Rust) - Experience with large-scale, high-concurrent production serving - Experience with GPU inference engines (vLLM, SGLang, Triton, TensorRT-LLM, etc.) - Strong background in system optimizations: batching, caching, load balancing, parallelism - Low-level inference optimizations: GPU kernels, code generation - Algorithmic inference optimizations: quantization, speculative decoding, distillation, low-precision numerics - Experience with testing, benchmarking, and reliability of inference services - Experience designing and implementing CI/CD infrastructure for inference Compensation and Benefits: - $180,000 - $440,000 USD - Equity compensation - Medical, vision, and dental coverage - 401(k) retirement plan - Short and long-term disability insurance - Life insurance - Additional discounts and perks SpaceXAI is an equal opportunity employer. For details on data processing, view our Recruitment Privacy Notice.

🏢 Summary: Role focused on solving critical AI modeling challenges in a hands-on, high-performance environment with strong emphasis on useful AI systems and engineering excellence. Candidates will work on impactful projects with clarity on initial responsibilities before receiving an offer. The position offers high compensation, equity, and comprehensive benefits. 🗂️ Requirements: Belief in truth-seeking AI systems, Experience as a power user of AI models, Strong communication skills, Hands-on engineering mindset, Ability to thrive in meritocratic environments, Strong work ethic, Strong prioritization skills 📃 Skills: AI, Modeling, Engineering 🏢 Description: SpaceXAI'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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: You will work on the most critical modeling challenges at any given time. You will get clarity on your first project before an offer. BASIC QUALIFICATIONS: You believe truth-seeking AI is the most important and challenging problem. You are obsessed about building incredibly useful models. You are a power user of AI models. If you previously trained models used by millions of people it's a big plus, but modeling experience is not required. You take pride in your work and thrive in meritocratic environments. COMPENSATION AND BENEFITS: $180,000 - $600,000 USD Base salary is just one part of our total rewards package, 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. Equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.

🏢 Summary: Opportunity to work on critical AI modeling challenges in a hands-on, high-performance environment focused on building highly useful AI systems. The role emphasizes initiative, strong communication, and collaboration within a flat organizational structure. Compensation includes a high base salary, equity, and comprehensive benefits. 🗂️ Requirements: Belief in truth-seeking AI as an important problem, Strong interest in building useful AI models, Power-user experience with AI models, Strong communication skills, Ability to work hands-on in a meritocratic environment, Strong prioritization and work ethic 📃 Skills: AI, Modeling 🏢 Description: SpaceXAI'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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: You will work on the most critical modeling challenges at any given time. You will get clarity on your first project before an offer. BASIC QUALIFICATIONS: You believe truth-seeking AI is the most important and challenging problem. You are obsessed about building incredibly useful models. You are a power user of AI models. If you previously trained models used by millions of people it's a big plus, but modeling experience is not required. You take pride in your work and thrive in meritocratic environments. COMPENSATION AND BENEFITS: $180,000 - $600,000 USD Base salary is just one part of our total rewards package, 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. Equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.

🏢 Summary: Opportunity to work on critical AI modeling challenges in a hands-on, high-performance environment focused on building useful truth-seeking AI systems. The role emphasizes initiative, strong communication, and engineering excellence, with flexibility around prior large-scale model training experience. 🗂️ Requirements: Belief in truth-seeking AI as a critical problem, Experience using AI models extensively, Strong communication skills, Ability to work hands-on in a flat organization, Strong prioritization and work ethic, Ability to contribute directly to AI modeling challenges 📃 Skills: AI, Modeling 🏢 Description: SpaceXAI'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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: You will work on the most critical modeling challenges at any given time. You will get clarity on your first project before an offer. BASIC QUALIFICATIONS: You believe truth-seeking AI is the most important and challenging problem. You are obsessed about building incredibly useful models. You are a power user of AI models. If you previously trained models used by millions of people it's a big plus, but modeling experience is not required. You take pride in your work and thrive in meritocratic environments. COMPENSATION AND BENEFITS: $180,000 - $600,000 USD Base salary is just one part of our total rewards package, 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. Equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.

🏢 Summary: Role focused on solving critical AI modeling challenges within a hands-on, high-performance environment centered on building highly useful truth-seeking AI systems. Candidates are expected to contribute directly, communicate effectively, and thrive in a meritocratic culture with strong ownership and prioritization. 🗂️ Requirements: Belief in truth-seeking AI systems, Experience as a power user of AI models, Strong communication skills, Hands-on contribution mindset, Strong prioritization skills, Ability to thrive in meritocratic environments, Focus on building useful AI models 📃 Skills: AI, Modeling 🏢 Description: SpaceXAI'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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: You will work on the most critical modeling challenges at any given time. You will get clarity on your first project before an offer. BASIC QUALIFICATIONS: You believe truth-seeking AI is the most important and challenging problem. You are obsessed about building incredibly useful models. You are a power user of AI models. If you previously trained models used by millions of people it's a big plus, but modeling experience is not required. You take pride in your work and thrive in meritocratic environments. COMPENSATION AND BENEFITS: $180,000 - $600,000 USD Base salary is just one part of our total rewards package, 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. Equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.

🏢 Summary: Applied Engineer role focused on building and scaling recommendation systems, ranking algorithms, and AI-driven search technologies for products serving hundreds of millions of users. The position involves developing machine learning infrastructure, real-time experimentation, and large-scale deep learning applications using modern AI frameworks and data systems. 🗂️ Requirements: Knowledge of Kafka, Clickhouse, and Spark, Experience implementing recommender systems at industrial scale, Experience with deep learning applications at industrial scale, Proficiency in JAX or PyTorch, Ability to design scalable machine learning systems, Strong communication skills, Hands-on engineering approach 📃 Skills: Kafka, Clickhouse, Spark, JAX, PyTorch, CUDA, Python, AI, ML 🏢 Description: SpaceXAI'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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: We're seeking exceptional Applied engineers to join a high-priority project that approximately 600 million monthly users use. This is an exciting opportunity for individuals with an engineer or scientist background to apply their skills to recommendation systems, ranking algorithms, search technologies, and many other systems. You'll work at the intersection of advanced AI development and real-world impact, enhancing the ability to connect users with relevant content, accounts, and experiences. RESPONSIBILITIES: - Designing and architecting recommendation algorithms across various product surfaces - Leverage all of xAI's infra and AI stacks to dramatically enhance the user experience - Write data pipelines and training jobs that continuously learn from product data - Iterate and improve the algorithm by gathering user feedback in real time through experimentation - Ensuring scalability and efficiency of machine learning systems BASIC QUALIFICATIONS: - Knowledge of data infrastructure like Kafka, Clickhouse, and Spark - Experienced in implementing recommender systems and/or deep learning applications at industrial scale - Skilled in one or more DL software frameworks such as JAX or PyTorch - Exceptional candidates may be experienced in writing CUDA kernels COMPENSATION AND BENEFITS: - $180,000 - $440,000 USD - Base salary is one part of the total rewards package and includes equity, comprehensive medical, vision, and dental coverage, access to a 401(k) retirement plan, short and long-term disability insurance, life insurance, and additional discounts and perks. SpaceXAI is an equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.

🏢 Summary: The role involves tackling the company’s highest-priority product or technical challenges in a hands-on engineering environment focused on truth-seeking AI. Candidates are expected to be exceptional software engineers who thrive in meritocratic, high-performance teams with strong communication and prioritization skills. 🗂️ Requirements: Exceptional software engineering skills, Strong communication skills, Ability to work hands-on in a flat organizational structure, Strong prioritization skills, Ability to thrive in meritocratic environments, Interest in truth-seeking AI challenges 📃 Skills: AI, Software, Engineering 🏢 Description: SpaceXAI'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 employees are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates. ABOUT THE ROLE: You will work on the most critical product or technical challenge at any given time. You will get clarity on your first project before an offer. BASIC QUALIFICATIONS: You believe truth-seeking AI is the most important and challenging problem. You take pride in your work and thrive in meritocratic environments. You are an exceptional software engineer. COMPENSATION AND BENEFITS: $180,000 - $440,000 USD Base salary is just one part of our total rewards package, 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. Equal opportunity employer. For details on data processing, view the Recruitment Privacy Notice.