Software Engineer, Model Lifecycle and Signals

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.

SOFTWARE ENGINEER, MODEL LIFECYCLE AND SIGNALS

As a Software Engineer on the Model Lifecycle and Signals team at SpaceXSI, you'll own the bridge between frontier models and every user-facing Cursor product, used at a scale few teams ever see. You'll decide when we use which model, spot where models go off track and build the guardrails to keep them on it, and shape what the next generation of models should learn. This role sits at the intersection of infrastructure, data, and product: you'll bring models from preview to production, dig into real-world data to find out what's actually working, and partner with research, inference, product, and data science teams to turn that evidence into better products and better models. Every improvement you make compounds across our products and every model we ship.

RESPONSIBILITIES:

• Get new frontier models into users' hands the day they're ready, and retire old ones without anyone noticing

• Evaluate internal and external preview models before launch and give meaningful feedback to the teams building them

• Build Cursor Router (https://cursor.com/docs/cursor-router): decide which model handles each request, balancing quality, speed, and cost at massive scale

• Build the eyes and ears of the product, and the experimentation platform that puts them to work: signals that show where each model shines, where it goes off track, and what "better" actually means

BASIC QUALIFICATIONS:

• Bachelor's degree in computer science, engineering, math, or scientific discipline; OR 2+ years of professional experience building software in lieu of a degree

PREFERRED SKILLS AND EXPERIENCE:

• Track record of shipping production systems people rely on, owning problems end to end, and automating painful processes rather than repeating them

• Experience building and operating evaluation, measurement, or model serving systems, such as AI evals, experimentation, ranking/relevance, or routers

• Ability to turn ambiguous "quality" questions into concrete metrics, pipelines, and decisions

• Fluency with data and the ability to collaborate effectively with data scientists and researchers

• Taste and real curiosity about model and agent behavior, including trying new models the day they come out and forming opinions about where each one shine

ADDITIONAL REQUIREMENTS:

• Onsite role: must be able to work in person at the New York or San Francisco office

COMPENSATION AND BENEFITS:

The annual compensation range for this role is listed below.

Annual Salary:

$140,000 - $225,000 USD

Your actual level and base salary will be determined on a case-by-case basis and may vary based on the following considerations: job-related knowledge and skills, education, and experience.

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.

Department: Engineering