Founding Product Engineer at River

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.

• 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.

• Holds 2–4 years of professional experience as an IC, with a deep mastery of TypeScript and Node.js used to ship and maintain software with real users.
• Possesses hands-on experience with LLM APIs and can clearly articulate the challenges and solutions required to make generative model outputs reliable for production use.
• Demonstrates a true 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.

• Join as the first hire alongside two founders, directly shaping the technical foundation and product direction of a high-growth AI company where demand already outpaces capacity.
• Benefit from a powerhouse cap table featuring the founders of Ramp, Kalshi, and JumpCloud, providing both world-class mentorship and a strong signal of market fit.
• 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.