Magic’s mission is to build safe AGI that accelerates humanity’s progress on the world’s most important problems. We believe the most promising path to safe AGI lies in automating research and code generation to improve models and solve alignment more reliably than humans can alone. Our approach combines frontier-scale pre-training, domain-specific RL, ultra-long context, and inference-time compute to achieve this goal.

About the role

As a Software Engineer on the Pre-training Data team, you will design and operate the systems that define our model’s training corpus at scale.

This role is focused on large-scale data acquisition, processing, filtering, mixture design, and ablation-driven iteration. You will work on the infrastructure and experimental loops that determine what data we train on — and therefore what the model learns.

Magic’s long-context models introduce non-trivial data challenges: maintaining document structure and long-range coherence, designing sequence chunking and packing strategies, balancing mixture trade-offs, and ensuring data quality at internet scale. You will own systems that turn these questions into measurable training decisions.

This role can evolve into broader ownership of corpus strategy, deeper involvement in training systems, or transition into ML systems work as you shape how data and model behavior interact at scale.

What you’ll work on

• Build and operate large-scale web crawling, scraping, and ingestion pipelines

• Design filtering, deduplication, quality controls, and dataset versioning systems

• Run data ablations across sources, rewrites, mixtures, and long-sequence strategies

• Optimize distributed data processing systems for throughput and cost efficiency

• Improve observability and reliability of large ETL and dataflow jobs

• Collaborate with Research and Training Systems teams to align corpus design with model behavior

What we’re looking for

• Strong software engineering fundamentals

• Experience building and operating large-scale distributed data systems

• Ability to design and interpret practical data ablation experiments

• Comfort making decisions under compute, storage, and cost constraints

• Strong systems intuition around reliability and scale

• Track record of owning production systems end-to-end

Compensation, benefits, and perks (US):

• Annual salary range: $200K - $550K

• Equity is a significant part of total compensation, in addition to salary

• 401(k) plan with 6% salary matching

• Generous health, dental and vision insurance for you and your dependents

• Unlimited paid time off

• Visa sponsorship and relocation stipend to bring you to SF, if possible

• A small, fast-paced, highly focused team

Magic strives to be the place where high-potential individuals can do their best work. We value quick learning and grit just as much as skill and experience.

Our culture

• Integrity. Words and actions should be aligned

• Hands-on. At Magic, everyone is building

• Teamwork. We move as one team, not N individuals

• Focus. Safely deploy AGI. Everything else is noise

• Quality. Magic should feel like magic