Founding Product Engineer ($150k-$190k + Equity) at River

About the role

River is a pre-seed AI startup backed by the founders of Ramp, Kalshi, and JumpCloud, building sophisticated voice agents that conduct live B2B sales calls. The platform enables agents to speak in real-time while autonomously driving a browser to demo products, closing the loop from initial contact to deal closure. As the first engineering hire at River, you will build AI voice agents that autonomously drive browsers and conduct real-time sales calls. Working directly with founders and design partners, you’ll own the full-stack experience from the live call interface to complex LLM integrations, iterating weekly based on real-world performance. Located in New York, USA.

Responsibilities

• Lead full-stack development with a focus on the live call experience, agent-driven demos, and the core dashboard surfaces used by enterprise design partners.
• Partner directly with customers to learn their specific sales motions, then rapidly build, deploy, and monitor the agents during live production calls.
• Engineer robust systems around LLM APIs to ensure high reliability and low latency, moving beyond prototypes to production-grade software that handles mission-critical sales interactions.

Requirements

• 2–4 years of professional experience as an individual contributor, with deep mastery of TypeScript and Node.js used to ship and maintain software with real users.
• Hands‑on experience with LLM APIs and ability to articulate the challenges and solutions required to make generative model outputs reliable for production use.
• Demonstrated builder’s pedigree, evidenced by a history of launching side projects with traction, founding a startup, or shipping 0–1 products at high‑bar companies.

Benefits

• Equity compensation (in addition to salary).
• Access to a powerhouse cap table featuring the founders of Ramp, Kalshi, and JumpCloud, providing world‑class mentorship and a strong signal of market fit.
• Opportunity to solve complex, real‑time engineering challenges involving voice AI, WebRTC, and browser automation to build a product that generates immediate revenue and tangible customer value.

Pay

$150k–$190k base salary plus equity.