The build: Our client is hiring a Founding Reinforcement
Learning Engineer to build the core RL systems from the ground up. You'll work
directly with the founders, own the full loop from environment design to
training to evaluation, and help shape the technical direction of the company.
What you'll do
- Design
and build RL environments, reward functions, and training pipelines.
- Train
and fine-tune models with RL methods (PPO, GRPO, DPO, RLHF/RLAIF and
similar).
- Build
evaluation frameworks to measure model and agent performance.
- Run
experiments fast, read results, and decide what to try next.
- Scale
training on GPU clusters and keep pipelines reliable.
- Turn
research ideas into production systems.
- Help
set engineering culture and hire the next engineers.
Requirements
What we're looking for
- 2+
years of hands-on experience in reinforcement learning or ML engineering.
- Strong
Python skills and deep experience with PyTorch (or JAX).
- Hands-on
work training models with RL (policy gradient methods, reward modeling,
RLHF or similar).
- Experience
with LLM post-training or agent training is a big plus.
- Comfortable
with distributed training and GPU infrastructure.
- Builder
mindset: you ship fast and are happy in a small, early team.
- Degree
in CS, Math, Physics, or a related field (MS/PhD a plus).
- Publications
or open-source work in RL.
- Experience
at an AI lab or an early-stage AI startup.
- Experience
with simulation or environment frameworks (Gymnasium, Ray RLlib, Isaac,
MuJoCo).
- Experience
with training libraries like TRL, verl, or OpenRLHF.
Skills Required
- 2+ years of hands-on experience in reinforcement learning or machine learning engineering
- Strong Python skills and deep experience with PyTorch or JAX
- Hands-on experience training models with reinforcement learning, including policy gradient methods, reward modeling, RLHF, or similar
- Experience with distributed training and GPU infrastructure
- Builder mindset and ability to work effectively in a small, early-stage team
- Degree in computer science, mathematics, physics, or a related field
- Experience with LLM post-training or agent training
- Publications or open-source work in reinforcement learning
- Experience at an AI lab or early-stage AI startup
- Experience with simulation or environment frameworks such as Gymnasium, Ray RLlib, Isaac, or MuJoCo
- Experience with training libraries such as TRL, verl, or OpenRLHF
- MS or PhD degree
What We Do
Fruition Executive Search is a boutique executive search firm based in San Francisco. They specialize in sourcing high-caliber leadership talent across various industries, including Accounting, Finance, AI, Software, and Healthcare. Utilizing a dual approach of retained and contingent search, they connect organizations with C-suite and management professionals equipped to drive strategic direction, profitability, and digital transformation through human-centered leadership.
