Product Engineer (Full-Stack)

We are looking for a Product Engineer with 2-5 years of experience to join River as the first engineering hire outside the founding team. You'll build the AI voice agents that run live B2B sales calls — from backend services to browser-use demos — shipping to production weekly and working directly with the founders at a company that just turned on revenue and is scaling fast.

What will you be doing?

- Building backend services and APIs behind live AI sales calls (session state, integrations, data pipelines)

- Developing the browser-use agent that navigates and demos real products live while the AI talks to prospects

- Working directly with design partners to shape the product — understanding their needs and building custom solutions that feed back into core product

- Building LLM-powered workflows: prompts, tool use, and agentic flows the agent follows during live demos

- Shipping UI in Next.js/React where needed, watching real calls, and iterating fast

Key Requirements

- 2-5 years of professional software engineering experience with shipped production software

- Strong TypeScript/JavaScript skills, particularly on the backend (Node.js, Next.js, Postgres)

- Hands-on experience building with LLMs or real-time applications

- High ownership mindset — can independently find problems, make decisions, and ship without hand-holding

- Must be based in or willing to relocate to New York City (in-office role)