Full-Stack Product Engineer ($90k-$140k + Equity) at River

River is a New York-based AI startup building autonomous voice agents for B2B sales teams, backed by the founders of Ramp, Kalshi, and JumpCloud. The company's AI seller qualifies leads, answers questions, and performs live product demos by navigating browsers in real time to drive deals to close 24/7.

About the role

As a Full-Stack Product Engineer at River, you will build the core infrastructure powering live AI sales interactions. You will develop backend services for session state, engineer sophisticated LLM workflows, and create browser-automation agents for live demos. Joining a small founding team, you will ship to production daily in a high-intensity, in-person New York environment.

Why this role is remarkable

• Join a high-velocity founding team backed by elite investors and the founders of category-defining companies like Ramp and Kalshi.
• Work at the frontier of AI by building agents that perform complex, real-time product demonstrations in a live browser environment.
• Experience true product ownership with the autonomy to identify problems, build solutions, and ship features to production on a daily basis.

Responsibilities

• Build the backend services and data pipelines behind live AI calls, managing session state and complex integrations using Node.js and Postgres.
• Engineer LLM-powered workflows using OpenAI and Anthropic APIs to handle sophisticated prompting, tool use, and automated demo flows.
• Develop and maintain the browser-use agent using Playwright to navigate live product environments seamlessly during customer interactions.

Requirements

• 1-3+ years of experience shipping production-grade software in TypeScript and Node.js with a strong focus on backend architecture and data.
• Proven track record of building and launching real products using LLM APIs, demonstrating an understanding of reliability and performance.
• High-ownership mindset with the ability to thrive in a scrappy, in-office startup culture without the need for detailed specifications.

Pay

$90k-$140k + Equity

Location

New York, USA