Software Engineer - Network (C++)

About the role

At xAI, we design, build, and operate Colossus from the ground up. This includes the massive GPU clusters, high-speed interconnect fabric, and the software that makes it all work at unprecedented scale. Colossus powers Grok and our frontier AI models with a custom, high-performance datacenter network that delivers ultra-low latency and massive bandwidth across hundreds of thousands of GPUs.

Responsibilities

• Develop routing and traffic-engineering algorithms for the Colossus high-performance datacenter network.
• Develop highly reliable, real-time software designed to run on the switches that form the backbone of our low-latency, high-bandwidth AI training fabric.
• Participate in and lead architecture, design, and code reviews.
• Develop prototypes and run experiments to validate key design decisions at both small and full-cluster scale.
• Build tools for software development, deployment, data analysis, visualization, and testing across virtualized environments, hardware-in-the-loop setups, and live production clusters.
• Deploy reliable software updates through continuous integration and release systems with rigorous testing and monitoring.

BASIC QUALIFICATIONS

• Bachelor’s degree in computer science, engineering, math, or a related technical discipline; OR 2+ years of professional software development experience in lieu of a degree.
• Strong development experience in C or C++.

PREFERRED SKILLS AND EXPERIENCE

• Strong professional experience writing high-performance C/C++ in production environments.
• Experience developing, debugging, and deploying software that runs at scale in real-world systems.
• Deep knowledge of networking protocols (UDP, TCP/IP, RDMA, etc.), distributed systems, and large-scale datacenter fabrics.
• Background in real-time systems, high-performance computing, low-latency networking, or resource-constrained environments.
• Creative problem-solving ability with exceptional analytical skills and strong engineering fundamentals.
• Excellent written and verbal communication skills.
• Ability to thrive in a fast-paced, dynamic environment with evolving requirements.
• Experience with security considerations in large-scale distributed systems.

ADDITIONAL REQUIREMENTS

• Must be willing to work extended hours and weekends as needed.

COMPENSATION AND BENEFITS

$180,000 - $440,000 USD
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. For details on data processing, view our Recruitment Privacy Notice.