ReflectionAI

Member of Technical Staff - Data Quality Engineer (Pre-training)

San Francisco · Staff+

H1B sponsorship availableDetected 194 days ago

PythonMachine LearningData EngineeringLLMsResearchCommunication

About the role

Data is playing an increasingly crucial role at the frontier of AI innovation.
Many of the most meaningful advances in recent years have come not from new architectures, but from better data.
As a member of the Data Team, your mission is to ensure that the data used to train our models meets a high bar for quality, reliability, and downstream impact.

Reflection is a research lab making intelligence open and accessible for everyone to use, customize, and build on.
We build open models that let anyone control their intelligence and help shape the future of AI.
Own upstream data quality for LLM pre-training; as a specialist or generalist across languages and modalities
Partner closely with research and pre-training teams to translate requirements into measurable quality signals, and provide actionable feedback to external data vendors
In addition to human-in-the-loop processes, you will design, validate, and scale automated QA methods to reliably measure data quality across large campaigns
Build reusable QA pipelines that reliably deliver high-quality data to pre-training teams for model training
Sponsorship support: We sponsor visas to help exceptional talent join our team and support long-term immigration pathways where applicable.
Team building: We have regular off-sites, happy hours, and team celebrations.
Joining Reflection means building from the ground up as part of a talent-dense team.

Solid understanding of how data quality impacts pre-training, with the ability to translate quality concerns into concrete signals, decisions, and feedback
Experience designing and validating automated quality checks, including rule-based systems, statistical methods, or model-assisted approaches such as LLM-as-a-Judge
Proficiency in Python and building ML / LLM workflows.
Must be comfortable debugging and writing scalable code
Experience working with large datasets and automated evaluation or quality-checking systems
Familiarity with how LLMs work and can describe how models are trained and evaluated
Excellent communication skills with the ability to clearly articulate complex technical concepts across teams
Proficiency in Python and building ML / LLM workflows. Must be comfortable debugging and writing scalable code

Salary and equity structured to recognize and retain our talent globally.
Health & wellness: Comprehensive medical, dental, vision, and life, with an annual wellness allowance.

Top-tier compensation: Salary and equity structured to recognize and retain our talent globally.
Stock options: Everyone who joins and contributes to Reflection's success gets to share in the upside through stock options.
Health & wellness: Comprehensive medical, dental, vision, and life, with an annual wellness allowance.
Life & family: 22 weeks paid parental leave for all new birthing and non-birthing parents, including adoptive and surrogate journeys.
Vacation days: Unlimited paid time off in the U.S. and 30 days in the U.K.

We sponsor visas to help exceptional talent join our team and support long-term immigration pathways where applicable.

This listing is sourced directly from ReflectionAI's careers page and normalized into a canonical job model.