LMArena · 3 weeks ago
Machine Learning Scientist - Open Source Lead
San Francisco Bay Area
Full-time
Hybrid
Senior LevelLMArena is the open platform for evaluating how AI models perform in the real world. They are seeking a Machine Learning Scientist to lead open-source research, design experiments, and develop methodologies that enhance the evaluation and understanding of AI models, while promoting transparency and collaboration within the research community.
Artificial Intelligence (AI)Information ServicesMachine LearningProduct Research
Responsibilities
Design and conduct experiments to evaluate AI model behavior across reasoning, style, robustness, and user preference dimensions
Develop new metrics, methodologies, and evaluation protocols that go beyond traditional benchmarks
Analyze large-scale human voting and interaction data to uncover insights into model performance and user preferences
Communicate results with the broader research community via academic papers, educational content, conference talks
Collaborate with engineers to implement and scale research findings into production systems
Prototype and test research ideas rapidly, balancing rigor with iteration speed
Partner with model providers to shape evaluation questions and support responsible model testing
Contribute to the scientific integrity and transparency of the LMArena leaderboard and tools
Qualification
Required
Hands-on experience training large-scale models, including reward models, preference models, and fine-tuning LLMs with methods like RLHF, DPO, and contrastive learning
Strong foundation in ML and statistics, with a track record of designing novel training objectives, evaluation schemes, or statistical frameworks to improve model reliability and alignment
Fluent in the full experimental stack, from dataset design and large-batch training to rigorous evaluation and ablation, with an eye for what scales to production
Deeply collaborative mindset, working closely with engineers to productionize research insights and iterating with product teams to align research with user needs
Comfortable being a visible representative of LMArena, engaging openly with the research community, and building a strong personal brand to help shape AI research culture
PhD or equivalent research experience in Machine Learning, Natural Language Processing, Statistics, or a related field
Uses personal and professional platforms to amplify open research initiatives and invite collaboration
Strong understanding of LLMs and modern deep learning architectures (e.g., Transformers, diffusion models, reinforcement learning with human feedback)
Proficiency in Python and ML research libraries such as PyTorch, JAX, or TensorFlow
Demonstrated ability to design and analyze experiments with statistical rigor
Experience publishing research or working on open-source projects in ML, NLP, or AI evaluation
Comfortable working with real-world usage data and designing metrics beyond standard benchmarks
Ability to translate research questions into practical systems and collaborate across engineering and product teams
Passion for open science, reproducibility, and community-driven research
Preferred
Skilled at public speaking, writing, and presenting research work to diverse audiences
Actively participates in conferences, panels, and online forums to foster relationships and thought leadership
Builds trust through transparent communication and consistent community engagement
Serves as a go-to contact for external researchers, journalists, and partners
Benefits
Comprehensive health and wellness benefits, including medical, dental, vision, and additional support programs.
Company
LMArena
LMArena is a web-based platform that evaluates large language models (LLMs) through anonymous, crowd-sourced pairwise comparisons.
Founded in 2025
11-50 employees
Funding
Current Stage
Early StageTotal Funding
$250M2026-01-06Series A· $150M
2025-05-21Seed· $100M
Leadership Team
Anastasios Angelopoulos
Chief Executive Officer
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