Sr. Model Engineer, Mid-Training

SpaceXSI·Palo Alto, CA·Posted 2 November 2026

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About the role

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:…

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