Sr. Model Engineer, Mid-training

xAI|02 Nov 2026

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Listed location: Palo Alto, CA

Work arrangement: onsite. A remote label does not confirm worldwide eligibility or visa sponsorship.

Read the employer’s description for qualifications, compensation and work eligibility. Confirm the position is still open on the application page.

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Job Description

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.

RESPONSIBILITIES:

Scale synthetic coding data to trillions of tokens with large-scale docker verification
Distill the intelligence of flagship models into flash models through synthetic data generation
Optimize mid-training data mixtures to boost the ceiling for RL
Engineer long-context data recipes
Develop robust and diverse evaluation for mid-training checkpoints

BASIC QUALIFICATIONS:

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)

PREFERRED SKILLS AND EXPERIENCE:

Familiarity across all kinds of scaling laws
Strong ability to design ML experiments
Familiarity with state-of-the-art techniques for curating AI training data for text, image, audio, and video modalities
Strong engineering abilities in large-scale data processing frameworks
Experience with ML and large model scaling
Experience with Spark, Ray, and other large-scale data processing frameworks

COMPENSATION AND BENEFITS:

$180,000 - $440,000 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.

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Is the Sr. Model Engineer, Mid-training position at xAI remote?

The Sr. Model Engineer, Mid-training role at xAI does not have a confirmed remote arrangement in our data. Check the employer description for its work location.