Experience training or serving large language models
Experience building RL environments or evaluation suites for LLMs
Proficiency in PyTorch, JAX, or similar ML frameworks
Strong experimental design skills
Master's or equivalent research experience
Responsibilities
Design and build the post-training stack for customer models
Own end-to-end experiments across data, training, and evaluation
Shape telemetry into learnable signals
Train and serve custom LLMs and agents
Design novel algorithms
Benefits
Opportunities to work directly with founders and design partners
Ability to influence core technical and product decisions
A chance to define the culture and architecture of the company
Engagement in innovative and foundational projects in AI and RL
Full Job Description
Job Description
As a Member of Technical Staff (Research) at Trajectory, you will design and build the post-training stack that lets our customers' models continually learn from real production workflows. You will own end-to-end experiments across data, training, and evaluation: shaping telemetry into learnable signals, training and serving custom LLMs and agents, and designing novel algorithms. You'll work directly with the founders and design partners, make foundational technical and product decisions, and help define both the culture and architecture of a company whose core mission is to enable continually learning intelligence.
Required Qualifications
Experience training or serving large language models
Experience building RL environments or evaluation suites for LLMs
Proficiency in PyTorch, JAX, or similar ML frameworks
Strong experimental design skills
Master's / research experience
Preferred
Background in pre- or post-training RL for LLMs
Experience with high-performance computing or large-scale clusters
Contributions to open-source ML research or infrastructure
Demonstrated technical creativity (research, OSS, side projects)
PhD (last year of PhD), working on AI / RL open source projects
