LLM Post-Training Engineering Lead (Forward-Deployed)

Visa Hunt; New York (NY); On-site; USD 180,000 - 240,000; Full time

Benefits offered by this job

Top-tier compensation

Stock options

Health & wellness

Meals provided

Parental leave

Job summary

Reflection is a research lab focused on making intelligence open and accessible, building open models you can customize and deploy. We seek a Forward Deployed Engineer Lead, Post-Training, to own the technical strategy for model customization from data generation to production deployment.

You will work with customers to understand their needs and collaborate with research teams to push what’s possible with our models, shaping the post-training and evaluation practice at scale.

Qualifications

• Hands-on post-training experience with large language models at scale.
• Experience building synthetic data generation pipelines, reward models, and verifiers for reinforcement learning workflows.
• Deep understanding of evaluation methodology and how to interpret training dynamics.
• Practical experience with training infrastructure at scale: multi-node GPU clusters, distributed training, and cost optimization.
• Strong software engineering fundamentals with production-quality code and reproducible workflows.

Responsibilities

• Lead post-training engagements with enterprise customers: assess data, define training strategies, design reward signals and verifiers, prepare datasets, run training loops, and evaluate results against customer-specific benchmarks.
• Design and build RL training environments, 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.
• Own the data pipeline from raw customer data through training-ready datasets, including synthetic data generation, data quality inspection, cleaning, and format standardization.
• Deploy post-trained models across hybrid environments (public cloud, VPC, on-premises), ensuring inference performance and cost efficiency at scale.
• Shape and scale the post-training practice by defining playbooks, best practices, and technical standards; mentor engineers on the team.

Skills

LLM post-training

RL training

Data pipelines

Software engineering

Customer-facing

Ownership

Multi-node GPU

Tools

Python

PyTorch

Git

Job description

Reflection is a research lab focused on making intelligence open and accessible, building open models you can customize and deploy. We seek a Forward Deployed Engineer Lead, Post-Training, to own the technical strategy for model customization from data generation to production deployment.

You will work with customers to understand their needs and collaborate with research teams to push what’s possible with our models, shaping the post-training and evaluation practice at scale.