ML Research Engineer - PhD - AI Trainer

Mercor; Seattle (WA); On-site; USD 100,000 - 150,000; Part time

Job summary

Obsidian in Seattle is hiring experienced machine learning engineers and researchers to act as human baseliners for open-ended machine learning evaluations. This role requires independent work in a sandboxed environment, completing ML tasks while providing screen recordings of the process.

Applicants need at least 3 years of machine learning experience and should have attended a top-100 university or worked at prominent companies. A commitment of 20 hours per week is required, and more availability is preferred.

Qualifications

• 3+ years of machine learning experience required.
• Must have attended a top-100 university or worked at FAANG.
• Experience with major ML frameworks like PyTorch, JAX, TensorFlow.

Responsibilities

• Attempt open-ended machine learning research tasks.
• Work independently in a sandboxed Linux environment.
• Record working session via screen recording.

Skills

Machine learning experience

Experience with PyTorch, JAX, or TensorFlow

Hands-on expertise in pretraining and fine-tuning

Education

Attended top-100 university or worked at FAANG

Job description

Overview

We are hiring experienced machine learning engineers and researchers to serve as human baseliners for evaluations of open-ended machine learning research tasks. These evaluations measure how well AI agents perform on realistic AI R&D problems. To interpret agent performance, we also need strong human reference points: skilled practitioners attempting the same tasks under the same time and compute constraints. As a baseliner, you will complete self-contained ML research tasks in a sandboxed environment, working independently with your preferred tools and workflow. Your performance will be used as a benchmark against which frontier-model agents are evaluated.

What You’ll Do

• Attempt open-ended machine learning research tasks under a fixed time and compute budget (work trial)
• Work independently in a sandboxed Linux environment with internet access
• Use your preferred tooling, including IDEs and AI coding assistants such as Cursor, Claude Code, and ChatGPT
• Record your full working session via screen recording
• Complete a short pre-task and post-task questionnaire
• Submit your final work product, screen recording, and completed questionnaires

Post this you will be hired for a longer commitment.

Commitment

• Minimum 20 hours per week if selected
• More availability is strongly preferred

Requirements

• 3+ years of machine learning experience (time spent in a PhD program counts toward this requirement; undergraduate and master’s experience does not count)
• Attended a top‑100 university or worked at FAANG or a comparable company
• Experience with at least one major ML framework such as PyTorch, JAX, or TensorFlow
• Deep, hands‑on expertise in at least one of the following focus areas:

• Pretraining under tight data and compute budgets
• PPO, reward shaping, custom gym / gymnasium environments, and throughput tuning
• Full fine‑tuning, LoRA, QLoRA, DPO, RLHF, RLAIF, and distillation
• Large‑scale corpus filtering, deduplication, subsampling, and benchmark contamination avoidance
• Architecture design under strict parameter‑count or size constraints
• Modifying pretrained architectures, including attention patterns, pooling heads, or training objectives
• Contrastive training for embedding or retrieval models
• Generative vision or video modeling
• Multilingual or low‑resource language experience
• Image or video data pipelines at scale
• Experience balancing competing model objectives such as safety and capability
• Prior work as an ML evaluator, red‑teamer, or baseliner

Required Domain Expertise

• Pretraining: training transformer language models from scratch
• Reinforcement learning: training agents in custom or existing environments
• Post‑training: fine‑tuning and aligning LLMs
• Dataset curation: building and cleaning large text corpora for LLM training
• Model architecture: designing and modifying neural network architectures

Logistics (work trial requirements)

• One baseline attempt per contractor per task
• Each task may only be attempted once by a given contractor
• All work is confidential and covered by NDA
• Compute and environment are provided; no personal GPU is required