Product Engineer

River; New York (NY); On-site; USD 120,000 - 190,000; Full time

Job summary

River in New York City is hiring an IC to work directly with the founders, shipping production-ready software and LLM-powered workflows. You will see your work used in live sales calls within the same week you build it, taking ownership without waiting for a spec.

You’ll build backend services, data pipelines, LLM prompts, and UI components (Next.js/React), collaborating with design partners to generalize wins into the product.

Qualifications

• 2.5–5 years of experience as an IC. You've shipped real software that real people used.
• CS degree from a strong university, or equivalent exceptional experience at top-tier companies.
• You've built something real with LLM APIs, not just tutorials.

Responsibilities

• Build the backend services and APIs behind live calls: session state, integrations, data pipelines.
• Build the LLM-powered workflows: prompts, tool use, and the flows the agent follows during a live demo.
• Build the enrichment pipeline that tells the agent who it's talking to before the call starts.
• Partner with design partners on custom solutions, then generalize the wins back into the product.
• Ship UI where it's needed (Next.js, React), watch real calls, and iterate fast.

Skills

LLM APIs experience

Ownership

Product sense

Ship real software

Backend development

Education

CS degree from a strong university

Equivalent exceptional experience

Tools

Next.js

React

Job description

We just closed a $2M pre-seed, backed by the founders of companies like Ramp, Kalshi, and JumpCloud. We turned on revenue recently and demand already outpaces what we can serve. This is our founders' second company — they built and sold the first.

About the role

You work directly with the founders, ship to production often, and see your work running in real sales calls the same week you build it. It's a high-ownership role for someone a few years into their career who is ready to own what they build without waiting for a spec.

What you'll do

• Build the backend services and APIs behind live calls: session state, integrations, data pipelines
• Build the LLM-powered workflows: prompts, tool use, and the flows the agent follows during a live demo.
• Build the enrichment pipeline that tells the agent who it's talking to before the call starts
• Partner with design partners on custom solutions, then generalize the wins back into the product
• Ship UI where it's needed (Next.js, React), watch real calls, and iterate fast

Requirements

• 2.5–5 years of experience as an IC. You've shipped real software that real people used
• CS degree from a strong university, or equivalent exceptional experience at top-tier companies
• You've built something real with LLM APIs, not just tutorials
• Product sense. You care how it feels to use, not only that it works
• High ownership. You find the problem, propose the fix, and ship it — no PM required
• Genuine track record of shipping serious work: products with real users or revenue, a startup attempt, accelerator experience, or something you launched and grew (beyond hobby side projects)

Nice to have

• Experience at a fast-growing, recently founded company (last ~10 years) with a high engineering bar — especially AI-product startups shipping LLM features
• Voice, video, or anything real-time (WebRTC a plus)
• Go-to-market / sales-tech tooling, automations, or exposure to the sales workflow

Culture fit:

We're a fast-moving team. We want AI-native builders who work differently and produce the output of a much larger team — people here for the ride and the mission, not just pay and stability.

Why River

• Small enough that everything you build matters, and you'll watch it run in real sales calls
• You work directly with the founders. No layers, no tickets handed down

Location

In-person in New York (4–5 days/week).

No visa sponsorship or relocation support.

Process

2–3 interviews, behavioral/culture screen, a short build-together technical session, and a possible final in-person round.

Additional Job Application Terms

This job is part of LinkedIn’s Full-Service Hiring beta program. Eligibility is limited to candidates located in and performing services in the United States, excluding those based in Alaska, Hawaii, Nevada, South Carolina, or West Virginia.