Join River as our first engineering hire to build high-performance voice AI agents. You will work directly with the founders in our New York office, owning significant parts of our real-time infrastructure and product features. This role is perfect for a backend-leaning full-stack engineer ready to define the architecture of a Tier-1-backed startup.
Founding Engineer, Full Stack at River
River is building the next generation of voice AI agents that don't just talk, but close deals and control browsers to demo products. As the first engineering hire alongside founders backed by the creators of Ramp and Kalshi, you'll own the core real-time infrastructure and ship features that define the product. If you have 3-7 years of experience, a high-ownership mindset, and a background in real-time streaming or Tier-1 venture-backed startups, this is your chance to build an AI-native company from the ground floor in New York.
What's the next step?
Jack finds you jobs at companies like River. Talk to Jack to get considered for roles that fit what you're great at.
Location
New York, United States
Compensation
$160k-$220k + 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
- Build and scale real-time voice AI infrastructure using TypeScript, Node, and Next.js, ensuring sub-second latency for live sales conversations and automated demos.
- Take full ownership of the production environment, managing everything from feature design and browser automation to deploys, monitoring, and incident response.
- Collaborate directly with founders to influence product direction, making critical architectural decisions and shipping features without waiting for external specs.
Who this is a fit for
- Has 3 to 7 years of hands-on IC experience shipping and running production software used by real people, with deep proficiency in TypeScript and Node.
- Possesses a track record of building real-world applications with LLM APIs and has experience with real-time streaming technologies like WebRTC, voice, or WebSockets.
- Demonstrates a high-ownership mindset with previous experience at Tier-1 venture-backed startups (e.g., Sequoia, a16z) or as a former technical co-founder.
Why this role is remarkable
- Work as the first engineering hire alongside founders backed by industry leaders from Ramp, Kalshi, and JumpCloud, enjoying significant equity and direct product influence.
- Solve complex, sub-second latency challenges in real-time voice AI and browser automation that go far beyond simple LLM wrappers or basic tutorials.
- Join a high-velocity, in-office culture in New York that prioritizes extreme ownership, shipping fast, and building AI-native tools that multiply individual output.
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.
Meet Jack
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.