Member of Technical Staff - Pre-Training Data

The role

This person will design and implement techniques for sourcing, curating, and filtering large-scale web, text, and code data. They will work with the pre-training research team to design and run data experiments and evaluate dataset changes.

What you will do

• Design and implement techniques for sourcing, curating, and filtering large-scale web, text, and code data.
• Develop data quality metrics and analyses that measure coverage, diversity, and representativeness across sources.
• Design and run data experiments with infrastructure teams to scale data systems.
• Investigate and mitigate data risks including privacy, safety, and licensing concerns.
• Evaluate dataset changes through ablations and scaling experiments.
• Publish and present research and share code, datasets, and insights.

Required qualifications

• Proficiency in Python.
• Familiarity with at least one deep learning framework (e.g., PyTorch or JAX).
• Experience debugging distributed workloads and writing code that scales.
• Bachelor’s degree or equivalent experience in Computer Science, Machine Learning, Physics, Mathematics, or a related discipline.
• Strong theoretical and empirical grounding.
• Clear written communication and the ability to explain complex technical ideas.

Nice to have

• A strong grasp of probability, statistics, and ML fundamentals.
• Experience with curation, preprocessing, and analysis of large-scale text or code datasets.
• Exposure to multimodal data is a plus.
• Background in data engineering, dataset construction, or large-scale web data processing for machine learning.
• Experience evaluating or improving training data quality, and knowledge of data ethics, safety, and licensing frameworks relevant to AI datasets.
• Contributions to open datasets, research publications, or data tooling.
• PhD in Computer Science, Machine Learning, Physics, Mathematics, or a related discipline; or equivalent industry research experience.

Benefits

• Salary and equity.
• Stock options.
• Comprehensive medical, dental, vision, and life.
• Annual wellness allowance.
• Lunch and dinner provided in the office daily.
• 22 weeks paid parental leave for all new birthing and non-birthing parents, including adoptive and surrogate journeys.
• Unlimited paid time off in the U.S.
• 30 days paid time off in the U.K.
• Sponsorship support for visas.
• Regular off-sites, happy hours, and team celebrations.

Before you apply

• This position may require access to technology or source code subject to the U.S. Export Administration Regulations.
• Any offer of employment may be conditioned on the Company's ability to provide access to technology or source code in compliance with U.S. export control laws.

About the company

Reflection is a research lab making intelligence open and accessible for everyone to use, customize, and build on. They build open models to help shape the future of AI.