# Software Engineer, Pretraining Data

- **Company:** Cursor
- **Location:** Palo Alto, CA, US (On-site)
- **Salary:** Salary not disclosed
- **Contract:** Full-time
- **Posted:** 2026-11-10

## 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.
SOFTWARE ENGINEER, PRETRAINING DATA
We're looking for Software Engineers to build the data systems behind our frontier models' initial training. You'll work on large-scale crawling, data platform, and pipeline infrastructure, turning raw dumps into the datasets our models train on, and making iteration with researchers fast and reliable.
RESPONSIBILITIES:
Data Platform
Build the platform that turns raw web, code, multimodal, and acquired data into training-ready datasets for frontier pretraining runs
Own the pipelines, orchestration, and tooling that make pretraining data iteration fast, reliable, observable, and reproducible at scale
Create clear signals for data quality, lineage, freshness, and pipeline health so researchers can trust what goes into each run
Partner with initial training, crawling, data quality, and acquisition teams to turn new data ideas into measurable improvements in loss, evals, and model capability
Data Quality
Build and own high-throughput, fully telemetered data pipelines that process frontier-scale data with end-to-end traceability. If something breaks or drifts, your systems will tell us before the training run does
Train and ship models that classify, rank, filter, clean, and identify data at extreme throughput. These models have to be both accurate and fast enough to sit in the critical path without becoming the bottleneck
Design and run scaling-ladder experiments on data-mixture, repeatability, and quality depth that turn "this dataset feels good" into hard evidence the training team can trust
Partner tightly with Data Acquisition to hunt down missing or low-quality sources, and with the training teams to close the loop on what actually moves loss and downstream evals
Treat data quality as a systems problem and a research problem. You will write performance-critical code one week and design careful experiments the next
Crawling
Build and scale the web crawling systems that discover, schedule, fetch, and parse high-quality documents across the open web for initial training
Improve URL seeding, scoring, and fair host scheduling so crawl capacity lands on the hosts and pages that matter most for model quality
Raise crawl success and parsing quality, defeating antibot failures, improving extractors, and capturing content we previously could not get cleanly
Debug and harden complex crawl infrastructure end-to-end for availability, recovery, and ingestion lag, and automate delivery of crawl datasets into the data pipeline
Work independently (and alongside AI agents) and partner with Data Quality and Data Platform so new coverage shows up as better tokens in training runs
BASIC QUALIFICATIONS
Minimum of 3 years of software engineering experience
Software engineering experience building distributed systems and/or large-scale data infrastructure
PREFERRED SKILLS AND EXPERIENCE
High-slope engineer who has moved unusually fast (e.g., staff-level ownership within a few years) or brings relevant domain experience
Able to architect and ship end-to-end with high ownership, debug complex systems independently, and work alongside AI agents
Strong intuitions about large-scale distributed systems
Excited to learn how pre-training data shapes model quality, and want the ownership and visibility that comes with building systems that feed frontier training runs
ADDITIONAL REQUIREMENTS
Onsite role: must be able to work in person at the Palo Alto office
COMPENSATION AND BENEFITS:
The annual compensation range for this role is listed below.
Annual Salary:
$160,000 - $250,000 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.

[Apply on the company site](https://www.joonow.com/en/job/software-engineer-pretraining-data-palo-alto-ca-htpzv31n29/apply)