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

The post-training team at xAI transforms powerful pre-trained models into steerable, versatile models capable of understanding and addressing real-world challenges. As a Member of Technical Staff on the post-training team, you'll advance models for tool calling, reasoning, and model coordination. You'll work across language models of different scales, modalities, and specializations to create novel interactive paradigms. With a strong emphasis on interactivity and agentic behaviors, you will pioneer a new class of orchestration models to unlock seamless, real-time, human-AI collaboration.

Focus

• Enhance model capabilities in interactive tool calling, structured reasoning, and model orchestration, with a focus on real-time human-AI interactions and agentic decision-making.

• Enhancing data mixtures through data collection pipelines and generation techniques optimized for interactive human-AI collaborations and orchestration.

• Developing generalizable reward models and novel reinforcement learning algorithms to promote emergent interactive behaviors, enabling models to guide heavier backend systems.

• Designing robust evaluations that capture real-world interactive dynamics, human-AI synergy, and orchestration across diverse backend models, scales, and specializations.

• Implementing large-scale training frameworks for models that integrate and orchestrate backend models of varying sizes, skills, and capabilities in interactive, agentic environments.

• Collaborating with pre-training, reasoning, data, multimodal, applied, and product teams to expand interactive AI frontiers.

Ideal Experiences

• Expert in ML and training large language models.

• Track record in leading studies that significantly impacts AI advancement.

• Experience in data-driven large language model behavior improvements.

• Experience in advanced reinforcement learning or inference-time search techniques.

• Experience in developing benchmarks or large-scale distributed machine learning systems.

• Experience in model optimizations under complex setups (e.g., multi-modality, multi-context, multi-agent, long-horizon tasks, diverse user preference/feedback).

• Experience in model routing.

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.

Tech Stack

• Python

• Jax

• Py Torch

• Rust

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:

• One on one discussion & coding interviews (three meetings total)

• Project deep-dive: Present your past exceptional work to a small audience

Every application is reviewed by a member of our technical team. All interviews will be conducted via Google Meet.

Annual Salary Range

$180,000 - $440,000 USD

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. For details on data processing, view our *Recruitment Privacy Notice.