Member of Technical Staff - Research & Post-training

Preference Model

$150K — $200K *
Information Technology
Less than 5 years of experience
Job Overview by Ladders

Qualifications

  • Experience with end-to-end large language model post-training pipelines.
  • Proficiency in Python and experience with PyTorch or JAX.
  • Familiarity with at least one modern reinforcement learning training framework.
  • Experience in building and managing scalable machine learning infrastructure.

Responsibilities

  • Train and evaluate models to validate data quality and identify task coverage gaps.
  • Architect and optimize reinforcement learning training infrastructure and experiment management.
  • Design, implement, and test training environments and methodologies for RL agents.
  • Profile and optimize training runs to maximize research throughput and iteration speed.

Benefits

  • Competitive cash and equity compensation.
  • Ownership and autonomy in a startup environment.
  • Opportunity to collaborate with top machine learning engineers.
  • Comprehensive health, vision, and dental benefits.
  • 401K match offered.
  • Daily onsite lunch provided.
  • Weekly snack orders available.
  • Visa sponsorship and relocation support offered.
Full Job Description
About the Role

Models of the future will be able to train themselves on tasks that they are not good at. We are interested in investigating how far we can push the boundaries of self-directed learning. We are looking for Research Engineers or Research Scientists to push the frontier of post-training on large language models in a role that blends research and engineering, requiring you to implement novel approaches and shape research directions.

What You Will Do:
  • Train and evaluate models on our proprietary RL environments to validate data quality, surface gaps in task coverage, and close the feedback loop between environment design and model capability.
  • Architect and optimize our RL training infrastructure, from training abstractions to distributed experiment management, using frameworks like Verl, OpenRLHF, or similar. Help scale our systems to handle increasingly complex research workflows.
  • Design, implement, and test training environments, evaluations, and methodologies for RL agents.
  • Profile and optimize training runs end-to-end, from data loading through reward computation, to maximize experiment throughput and shorten the research iteration cycle.
What We are Looking For
  • Experience running end-to-end LLM post-training pipelines
  • Proficiency in Python and PyTorch or JAX
  • Experience with at least one modern RL training framework
  • Experience building and operating ML infrastructure at scale


You may be a good fit if you also:
  • Have experience evaluating model outputs and building reward or evaluation signals
  • Stay current on post-training research and can translate papers into running code
  • Have strong opinions (loosely held) about how to structure RL training code for reproducibility and fast iteration
  • Can balance research exploration with engineering rigor
  • Have strong systems design and communication skills

Candidates don't need a PhD or extensive publications. Some of the best researchers have no formal ML training and gained experience building industry products. We believe adaptability combined with exceptional communication and collaboration skills are the most important ingredients for successful startup research.

What We Offer:
  • Competitive cash and equity compensation (>90th percentile)
  • Ownership and autonomy in a fast moving startup environment
  • Opportunity to work with top machine learning engineers
  • Health, vision, dental, benefits
  • 401K match
  • Lunch provided everyday onsite
  • Weekly snack orders
  • Visa sponsorship & relocation support available

We value diverse perspectives and experiences. If you're excited about this role but don't check every box, we still encourage you to apply.

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