Founding Product Engineer

This is a job that Jill, our AI Recruiter, is recruiting for on behalf of one of our customers. She will pick the best candidates from Jack's network. The next step is to speak to Jack. Job Title Founding Product Engineer Salary $150k-$190k + Equity Company Description 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. Job Description 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. Location New York, USA Why this role is remarkable 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. What You Will Do 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. The ideal candidate 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. Who are Jack & Jill? Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support. And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate. How does this work? Jack's an AI agent for job searching and career coaching. He works for you.Jill is the AI recruiter working for the company. She recruits from Jack's network.If it's a match and the company wants to meet you, they'll make the intro. In the meantime, if you'd like, Jack will send you excellent alternatives. We never post fake jobs This isn't a trick. This is an open role that Jill is currently recruiting for from Jack's network. Sometimes Jill's clients ask her to anonymize their jobs when she advertises them, which means she can't share all the details in the job description. We appreciate this can make them look a bit suspect, but there isn't much we can do about it. Give Jack a spin! You could land this role. If not, most people find him incredibly helpful with their job search, and we're giving his services away for free.