Founding Engineer

RIVER Founding Engineer About River River builds AI voice agents for B2B SaaS sales teams. Our agent talks with prospects in real time: it qualifies them, answers the hard questions, demos the product by actually using it in a browser while it speaks, and follows up until the deal closes. A full AI seller, available 24/7. 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 Every River conversation runs on a sub-second loop: speech, a rendered avatar, several LLMs, and an agent using a real browser, all live in front of our customers' buyers. Your job is to make that loop fast and rock-solid. Backend and infrastructure are your priority, but you'll build across the whole product with us. This is a founding role: you're a core member of the team, shaping what River becomes, not just keeping it running. Many decisions will be yours to own. What you'll do Own the live-call pipeline: real-time voice, avatar, and browser streaming in one sub-second loop Own the infrastructure behind it: deploys, scaling, observability, cost Push our browser-use agent forward. River demos real products by controlling a browser live, clicking and navigating complex apps while it talks, and making that reliable is one of the most interesting problems here Put the engineering foundations in place as the team grows: monitoring, incident response, testing, evals Ship product features across the stack, and talk to customers Requirements 3–10 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 Solid TypeScript and JavaScript, strongest on the backend (we use Next.js, Node, Postgres, Redis), comfortable in React 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 •Browser use / computer use, or browser automation (Playwright, Puppeteer, CDP) •Voice, video, or anything real-time (WebRTC a plus) •Go-to-market / sales-tech tooling, automations, or exposure to the sales workflow •Scraping, enrichment, or data pipelines Culture fit: We're a fast-moving team of serial builders. We want an AI-native engineer who owns their domain end to end, produces the output of a much larger team, and is here for the mission and the ride — not the perks. Why River A founding role, with meaningful equity and a whole domain that's yours from day one You work directly with the founders and shape the product, not just the infrastructure Genuinely interesting problems: real-time voice AI and browser-use agents, live in front of real customers Competitive comp: $170,000–$220,000 plus 1.0%–2.5% founding equity Try the product /start Location : In-person in New York (4–5 days/week). No visa sponsorship or relocation support. Process: 2–3 interviews — behavioral/culture screen, a 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. We’re committed to making our hiring process as smooth and timely as possible, and we understand that waiting to hear back can add to the anticipation. If you’re a potential fit, our team will reach out within two weeks to progress you to the next stage. If you don’t hear from us in that time, we encourage you to explore other opportunities with our team in the future, and we wish you the very best in your job search.