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Member of Technical Staff - Pre-Training Evals Infra

Reflection AI

New York, NY · San Francisco · London · Full-time · Onsite · Posted Oct 13, 2026

At a glance

Employment
Full-time
Workplace
Onsite
Location
New York, NY · San Francisco · London
Visa sponsorship
Visa sponsorship available

About the role

  • You will build the evaluation infrastructure that researchers use to understand model capabilities, guide training decisions, and assess readiness for release.
  • The role spans evaluation authoring, distributed execution, and results analysis, with a particular focus on pre-training.
  • You will work directly with researchers to make evaluations faster, more reliable, and easier to use, ensuring that the results accurately reflect the models being evaluated.

Responsibilities

  • Design and evolve evaluation abstractions, building clear APIs and data models for evaluation tasks, datasets, configurations, model outputs, and scores.
  • Build scalable, reliable execution infrastructure by developing distributed systems for evaluating model checkpoints throughout training and ahead of release.
  • Optimize evaluation and inference performance by profiling inference servers and distributed execution to improve throughput, GPU utilization, and time to results.
  • Establish evaluation correctness and reproducibility through validation and regression tests, versioned datasets and configurations, and preserved provenance.
  • Build researcher-facing tools and intuitive interfaces for inspecting model outputs, comparing checkpoints and experiments, and debugging unexpected behavior.
  • Operate and monitor evaluations as training progresses, track workloads and results, triage failures, and develop alerts and diagnostics.
  • Turn research needs into reusable systems by partnering directly with researchers to identify bottlenecks, prioritize improvements, and turn bespoke workflows into self-service tools.

Requirements

  • Strong proficiency in Python, C++, or Rust, with the ability to reason deeply about concurrency, memory behavior, and performance.
  • Experience designing, building, and operating reliable, maintainable distributed systems, with sound judgment about interfaces, failure modes, and architectural tradeoffs.
  • Working knowledge of model inference and evaluation, including how implementation and configuration choices can affect measured model quality.
  • Ability to investigate complex problems across system boundaries, follow evidence, and identify root causes.
  • Strong product judgment and experience translating the needs of researchers or other technical users into clear APIs and usable tools.
  • Comfort owning ambiguous problems end to end, prioritizing competing research needs, and balancing rapid delivery with long-term reliability and maintainability.
  • Attention to detail and the persistence to investigate subtle discrepancies in model outputs, evaluation results, and system behavior.

Benefits

  • Top-tier compensation including salary and equity
  • Stock options
  • Comprehensive medical, dental, vision, and life insurance
  • Annual wellness allowance
  • Lunch and dinner provided in the office daily
  • 22 weeks paid parental leave for all new birthing and non-birthing parents, including adoptive and surrogate journeys
  • Unlimited paid time off in the U.S. and 30 days in the U.K.
  • Visa sponsorship support and long-term immigration pathways where applicable
  • Regular off-sites, happy hours, and team celebrations

Skills

  • Python
  • C++
  • Rust
  • Distributed Systems

Reflection AI

Member of Technical Staff - Pre-Training Evals Infra

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