Research Engineer

About the role

Fonzi is an AI recruiting company. No job boards. No recruiter spam. Companies request to interview you and submit salary bids upfront. Every week, hiring managers at 250+ pre-vetted startups in NYC and San Francisco review a curated group of engineers. They're reading profiles optimized by our team to surface what matters: what you've built, how you think about systems, and whether you're the kind of engineer who ships. Companies on Fonzi are Applied AI startups, Frontier labs, Hypergrowth startups, PE firms starting lean AI teams and more. They're backed by investors like A16z, Sequoia Capital, General Catalyst, Y Combinator and more.

How it works:

• 5‑minute application – we reach out, learn what you're building and what excites you, and optimize your profile.
• Hiring managers review the cohort and request interviews with candidates they want.
• Companies submit competing salary bids directly to you.
• You only interview where you're genuinely interested.
• Completely free. We have an iMessage agent + humans in the loop you can text anytime with questions or requests to help handle scheduling and coordination.

Responsibilities

• Post‑training, RL and fine‑tuning pipelines for frontier and domain‑specific models.
• Evaluation systems that measure what models can actually do.
• Distributed training and research infrastructure at scale.
• Agents, world models and new architectures moving from paper to product.
• Open‑source models and research shipped to real users.

Requirements

• Have turned research ideas into working code: training runs, experiments and evals.
• Strong in Python and PyTorch, comfortable with distributed training and GPUs.
• Experience with LLM training, fine‑tuning, reinforcement learning or evaluation.
• Ability to read a paper, implement it and assess whether it actually works.
• Thrive in small teams where research and engineering sit side by side.
• 2‑8 years of experience in research engineering, ML or a related field.

Compensation

$170,000 to $250,000+ base salary depending on experience and role. Many positions include meaningful equity at pre‑seed through Series B stage companies.

Interview Process

• Screening conversation looking for communication skills, cultural fit and research curiosity.
• Technical deep‑dive on a past project, your experimental choices and what you learned.
• Coding or pairing session on ML implementation or experiment design.