# Sr. Model Engineer, Post-Training & RL at xAI

- Company: xAI
- What the company does: SpaceXAI builds Grok — frontier AI models for reasoning, voice, image generation, and more. Build with the Grok API. Backed by Lightspeed, Sequoia and a16z.
- Company website: https://x.ai/
- Type: Startups (AI role)
- Level: Senior
- Location: Palo Alto, CA
- Work setup: On-site
- Pay: $180K to $600K base salary per year (USD)
- Posted: 2026-11-02
- Apply by: 2026-12-17
- Apply: https://job-boards.greenhouse.io/xai/jobs/5280958007?utm_source=1752vc&utm_medium=careers
- Page: https://www.1752.vc/careers/jobs/xai-sr-model-engineer-post-training-and-rl/

## About the role

You will work on the most critical post-training and reinforcement learning challenges at any given time — including reward modeling, preference optimization (RLHF/DPO), and RL for improving reasoning, truthfulness, and real-world capabilities. Found on 1752vc Careers, the job board for startup and VC roles.

## What they're looking for

- Experience writing production-quality code in Python, PyTorch, JAX, Rust, or C++
- Experience training large models (e.g., pre-training, post-training, fine-tuning, or RL training of neural networks with 1B+ parameters)

Tags: Model

Source: 1752vc Careers, https://www.1752.vc/careers/jobs/xai-sr-model-engineer-post-training-and-rl/