ReflectionAI

Forward Deployed Engineer, Lead - LLM Post-training

New York · Senior

H1B sponsorship availableDetected 265 days ago

Node.jsData EngineeringLLMsResearchLeadership

About the role

This team works at the intersection of model adaptation, sovereign deployment, and enterprise deployment: taking Reflection's open-weight models and making them work for specific customer domains, tasks, and constraints.
You will work directly with customers to understand their needs and with research teams to push what's possible with our models.

Design and build RL training environments for model adaptation, including synthetic data generation pipelines, reward model training, and preference data collection workflows.
Design and build evaluation infrastructure: define what "better" means for each customer use case, build eval harnesses, curate test sets, and establish baselines that measure real-world performance.
Own the data pipeline from raw customer data through training-ready datasets, including synthetic data generation, data quality inspection, cleaning, and format standardization.
Deep understanding of evaluation methodology: how to design evaluations that measure what matters, how to interpret training dynamics, and how to tell the difference between a model that looks good on a benchmark and one that actually works.
6+ years of engineering experience, including 2+ years focused on LLM post-training in a leadership capacity (e.g., Tech Lead on a post-training team, Senior MLE owning preference optimization for a product, or Lead Applied Scientist running RL training pipelines in production).
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.

Hands-on post-training experience with large language models at scale.
Practical experience with training infrastructure at scale: comfortable working with multi-node GPU clusters, managing large training runs, debugging distributed training, and optimizing for cost.
Experience with data pipelines, version control for datasets and models, and reproducible workflows.
In either case, you are comfortable translating domain requirements into training strategies and delivering measurable outcomes.

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.

make intelligence open and accessible to all.
We're seeking an exceptional technical leader to build and scale Reflection's post-training and evaluation capabilities within the Applied AI team.
As a Forward Deployed Engineer Lead, Post-Training, you will own the end-to-end technical strategy for model customization, from synthetic data generation and reward modeling through training and production deployment.
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.
Role Overview
Lead post-training engagements with enterprise customers: assess their data, define training strategies, design reward signals and verifiers, prepare datasets, run training loops, and evaluate results against customer-specific benchmarks.
What We're Looking For

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.