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River AI

API for fine-tuning open-weight models

Member of Program Staff - Data

Natural Language Processing & LLMsConfirmed live in the last 24 hours
Full-timePalo Alto, CA, USAIn-person

About the Job

Requirements

  • A completed or in-progress Bachelor's degree or higher, or equivalent professional experience.
  • Extensive experience running large-scale data campaigns or post-training at a frontier AI company or research institution.
  • Exceptional oral and written communication skills.
  • Operational experience with hiring or managing human data labelers.
  • Evidence of expertise or top standing in a non-technical domain, such as literature, philosophy, history, economics, sociology, psychology, or political science.
  • A collaborative mindset and bias for action in a fast-paced environment.

Responsibilities

  • Build and oversee data campaigns that feed training pipelines for next-generation agents and personalization systems, working closely with research teams to determine needed data.
  • Create evaluations for general capabilities, model behavior, continual learning, and personalization.
  • Architect and deploy new clients and interfaces for collecting feedback from tutors and users, working closely with product and research team members.
  • Manage external partnerships with data labelers across a variety of campaigns.

Desired Qualifications

  • A BA, Master's, or Ph.D. in humanities, social science, or STEM.
  • Experience managing external partnerships and contracts.
  • Product judgment and the ability to reason backward from user needs, with ownership in navigating ambiguity.
  • Hands-on experience with large language model systems, including application programming interfaces, agents, tool calling, prompt iteration, evaluation frameworks, and inference constraints.
  • Familiarity with modern deep learning algorithms, including reinforcement learning and supervised fine-tuning.

About the Company

River AI

API for fine-tuning open-weight models

River AI helps developers and enterprises train, fine-tune, and own custom open-weight AI models using its River API, which focuses on open-weight models rather than a single lab-owned general model. The API supports LoRA fine-tuning and reinforcement learning on frontier open weights, featuring fast weight transfers, sampling-training consistency, elastic compute, and token-based billing that avoids idle GPU charges. It differentiates itself by enabling true ownership and control of models, offering a full-stack solution for training, fine-tuning, and deploying custom models without relying on a centralized general model. Its goal is to empower individuals and organizations to own, customize, and run their own AI systems with close-to-the-user control.

Company size
11-50
Company stage
Early VC
Total funding
$1.1B
Headquarters
Palo Alto, CA
Founded
2026

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