Multilingual Data Engineer for Large-Scale LLM Pipelines

Reflection; New York (NY); On-site; USD 140,000 - 210,000; Full time

Benefits offered by this job

Top-tier compensation

Stock options

Health & wellness

Meals in office

Parental leave (22 weeks)

Unlimited PTO (US)

Visa sponsorship

Team events

Job summary

Reflection in New York is seeking a researcher-engineer to design and operate multilingual data pipelines and advance our multilingual language model capabilities.

You will collaborate with pre-training, mid-training, and post-training teams to improve data quality, efficiency, and cultural fidelity across languages, while maintaining rigorous measurement and strong ownership in a fast-moving team. You will lead small projects and contribute to open foundational models.

Qualifications

• Strong software engineering fundamentals and comfort processing web-scale datasets in distributed environments.
• Experience building large-scale data pipelines for language models, machine translation, speech, or search — ideally covering more than one language.
• Fluency or working proficiency in at least one language other than English, and genuine curiosity about how languages differ.
• A rigorous, measurement-first mindset: you prove a data change helped rather than assuming it did.
• Navigate trade-offs between research objectives and practical engineering realities.
• Comfortable with ambiguity and high ownership in a small, fast-moving team. Passionate about advancing the frontier of intelligence.

Responsibilities

• Design and operate large-scale multilingual data pipelines — sourcing, cleaning, deduplication, language identification, and script normalization across high- and low resource languages.
• Define and enforce quality bars for multilingual corpora, including translation quality, cultural fidelity, toxicity, and contamination checks.
• Design and run scientific experiments to advance our understanding of scaling large language models to improve multilingual data efficiency.
• Lead small research projects independently while collaborating on larger initiatives.
• Build evaluation sets and diagnostics that expose where model behavior degrades by language, register, or domain, and close those gaps with targeted data.
• Work with pre-training, mid-training, and post-training teams to land measurable, step-function improvements in multilingual capability.

Skills

Software engineering

Data pipelines

Distributed systems

Multilingual NLP

Language proficiency

Ambiguity tolerance

Job description

Reflection in New York is seeking a researcher-engineer to design and operate multilingual data pipelines and advance our multilingual language model capabilities.

You will collaborate with pre-training, mid-training, and post-training teams to improve data quality, efficiency, and cultural fidelity across languages, while maintaining rigorous measurement and strong ownership in a fast-moving team. You will lead small projects and contribute to open foundational models.