xAI
Company
Hardcore Engineer - Reasoning Training
Job Description
This job posting has expired and no longer accepting applications.
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 and researchers are expected to have strong communication skills. They should be able to concisely and accurately share knowledge with their teammates.
About the Role
xAI is seeking experienced software engineers to design, implement, and optimize systems for large-scale distributed reinforcement learning. These systems are rapidly evolving and sit at the intersection of nearly all of our research and product teams.
Focus
- Design and implement state-of-the-art distributed RL systems
- Profile, debug, and optimize system performance
- Software and algorithm co-design with researchers
Ideal Experiences
- Experience building, debugging, and optimizing distributed training systems
- Experience with distributed reinforcement learning, LLM inference
- Experience with high-performance, large-scale distributed systems
- Proficiency with Python, async/concurrent programming, JAX, Rust
Tech Stack
- Python / Rust
- JAX, PyTorch, XLA
- CUDA, NCCL
Location
The role is based in the Bay Area [San Francisco and Palo Alto]. Candidates are expected to be located near the Bay Area or open to relocation.
Interview Process
After submitting your application, the team reviews your CV and statement of exceptional work. 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 questions. If you clear the initial phone interview, you will enter the main process, which consists of four technical interviews:
- Coding assessment in a language of your choice.
- Systems hands-on: Demonstrate practical skills in a live problem-solving session.
- Project deep-dive: Present your past exceptional work to a small audience.
- Meet and greet with the wider team.
Our goal is to finish the main process within one week. All interviews will be conducted via Google Meet.
Annual Salary Range
$180,000 - $440,000 USD
xAI is an equal opportunity employer and does not unlawfully discriminate based on race, color, religion, ethnicity, ancestry, national origin, sex (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender, gender identity, gender expression, age, disability, medical conditions, genetic information, marital status, military or veteran status, or any other applicable legally protected characteristics.
Qualified applicants with arrest or conviction records will be considered for employment in accordance with all applicable federal, state, and local laws, including the San Francisco Fair Chance Ordinance, Los Angeles County Fair Chance Ordinance for Employers, and the California Fair Chance Act.
For Los Angeles County (unincorporated) Candidates:
xAI reasonably believes that criminal history may have a direct, adverse and negative relationship on the following job duties, potentially resulting in the withdrawal of a conditional offer of employment:
- Access to information technology systems and confidential information, including proprietary and trade secret information, and/or user data;
- Interacting with internal and/or external clients and colleagues; and
- Exercising sound judgment.
Please mention that you found this job on MoAIJobs, this helps us grow. Thank you!

xAI
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