6mo ago
$180,000 - $600,000 USD/yr

Model Engineer, Post-Training & RL

United StatesUnited States·Palo Altolead
OtherSoftware EngineerMember Of Technical StaffSoftware Engineering
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Quick Summary

Overview

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.

Technical Tools
OtherSoftware EngineerMember Of Technical StaffSoftware Engineering

SpaceX was founded under the belief that a future where humanity is out exploring the stars is fundamentally more exciting than one where we are not. Today, SpaceX is actively developing the technologies to make this possible, with the ultimate goal of making life multiplanetary and expanding consciousness to the stars.

SpaceXSI is building Super Intelligence to help humanity understand the universe. Our teams are building the full Super Intelligence stack: from our Colossus supercomputers, to Grok models, to our suite of applications, including Grok Bot, Grok Build, Grok Imagine, Grok Voice, and X. We're creating a powerful flywheel where more compute trains better models, better models power more useful products, and what we learn from people using those products shapes what we build next.

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.

Requirements

~1 min read
  • Experience writing production-quality code in Python, PyTorch, JAX, Rust, or C++
  • You believe truth-seeking AI is the most important and challenging problem
  • You are obsessed about building incredibly useful models through post-training and RL techniques
  • You are a power user of AI models and eager to push the boundaries of what’s possible with reinforcement learning and alignment methods
  • If you previously worked on post-training, RLHF, or trained models used by millions of people it’s a big plus, but relevant experience is not required
  • You take pride in your work and thrive in meritocratic environments

What We Offer

~1 min read

$180,000 - $600,000 USD

Base salary is just one part of our total rewards package at SpaceXSI, 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.

SpaceXSI is an equal opportunity employer. For details on data processing, view our Recruitment Privacy Notice.

Location & Eligibility

Where is the job
Palo Alto, United States
On-site at the office
Who can apply
US

About this job

Pay per year
$180,000–$600,000 a year
473% above the $68,006 median for Other jobs on Jobera (131,969 salaries).
Who can apply
United States
Posted
185 days ago
Employer
has 309 open jobs on Jobera in 7 countries.

Listing Details

Posted
April 29, 2026
First seen
April 29, 2026
Last seen
October 31, 2026

Posting Health

Days active
184
Repost count
0
Trust Level
42%
Scored at
October 31, 2026

Signal breakdown

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Driven by artificial intelligence and human empathy.

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Model Engineer, Post-Training & RL$180,000 - $600,000 USD