As a Founding Product Engineer, you will build River’s core buyer-facing experience, including real-time voice calls and live browser-driven demos. You’ll work across the stack to develop agent logic, teach the AI new sales motions, and iterate rapidly based on real-time feedback from sales calls you helped ship earlier that week.
Founding Product Engineer at River
Join River as a Founding Product Engineer and build the future of sales with AI voice agents that don't just generate leads—they demo and close deals. Backed by the founders of Ramp, Kalshi, and JumpCloud, River is an early-stage NYC startup where you'll own the buyer-facing product experience from live WebRTC calls to browser-automated demos. With revenue already flowing and demand outpacing capacity, you'll work directly with repeat founders to ship code that impacts real customer calls within days.
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Location
New York, United States
Compensation
$150k-$190k + Equity
Company
River
Role overview
AI Sales
River builds AI voice agents that sell. Backed the founders of Ramp and Kalshi.
What you will do
- Develop the buyer-facing product surface using Next.js and React, specifically focusing on the real-time live call and interactive demo experience.
- Architect and refine the agent logic using LLM APIs and browser automation tools like Playwright to teach the AI how to demo complex SaaS products.
- Collaborate directly with customers to learn their specific sales motions and integrate those insights into the product’s core discovery and closing capabilities.
Who this is a fit for
- Has 2-4 years of experience with a strong TypeScript/React background and proficiency across the full stack including Node.js, Postgres, and Redis.
- Demonstrates deep interest or experience in real-time systems like WebRTC, browser automation, or building production-grade applications with LLM APIs.
- Possesses a strong product instinct and the drive to work in-person in NYC, preferring direct customer interaction over simply working through a ticket queue.
Why this role is remarkable
- Build a “Full AI Account Executive” that actually drives browsers and closes deals, moving beyond simple lead generation into high-stakes real-time automation.
- Join an elite team backed by the founders of Ramp and Kalshi, working alongside repeat founders who have already successfully exited their first company.
- Experience true founding-stage ownership where you onboard design partners yourself and see your code live on customer calls the same week it’s written.
How Jack & Jill work together
I get to know what you’re great at, then find roles you’d never find yourself.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.
I recruit from Jack’s network and make the intro when I spot a great match.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.
Jack gets to know what you're great at and what you want next, then searches 15 million jobs daily and helps you discover roles at companies like this.
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What happens next?
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 your profile’s a match and River wants to meet, Jill will make the intro. In the meantime, Jack will send you excellent alternatives.