Data Quality Engineer (Pre‑training)

About the role

As a member of the Data Team at Reflection, you will ensure that the data used to pre‑train our large language models meets the highest standards of quality and reliability. You will work closely with world‑class researchers to translate fuzzy notions of “good data” into concrete, measurable signals that drive model performance.

Key responsibilities

• Own upstream data quality for LLM pre‑training across languages and modalities.
• Partner with research and pre‑training teams to define quality signals and give actionable feedback to external data vendors.
• Design, validate, and scale automated QA methods and reusable pipelines for large‑scale data campaigns.
• Monitor data quality over time and iterate on standards, processes, and acceptance criteria.

Required profile

• Strong engineering fundamentals with experience building data pipelines, QA systems, or evaluation workflows for pre‑training data.
• Detail‑oriented analytical mindset able to identify subtle data quality issues and translate them into concrete signals.

Required skills

• Proficiency in Python and building ML/LLM workflows.
• Experience with large datasets and automated quality‑checking systems, including rule‑based and statistical methods.

What we offer

• Top‑tier compensation with salary and equity.
• Stock options, comprehensive health benefits, unlimited PTO (US) and 30 days (UK), and generous parental leave.
• Meals provided on‑site, visa sponsorship, and regular team‑building events.