Founding Backend Engineer

River (AI voice agents for B2B sales) | New York, NY | ONSITE | Full-time We build AI voice agents that run live B2B sales calls — real-time voice, browser-driven product demos, automated follow-up. We're pre-seed, backed by the founders of Ramp, Kalshi, and JumpCloud, revenue is on, and demand is already outpacing what we can serve. It's a genuinely fun problem, and we'd love to find the right people to build it with. We're hiring two founding engineers. To save everyone's time, here's what the role really needs — if a few of these are a strong yes, we'd love to hear from you: NYC-based and up for working in person (5 days). We're not able to do relocation or visa sponsorship right now. TypeScript/Node as your main production stack — the one you actually ship in day to day. You've shipped real software that real people used — something in production, with revenue, or a startup you built (not tutorials or coursework). You've built something real with LLM APIs. You like owning things end to end — finding the problem and fixing it without waiting for a spec. Two levels: Founding Backend Engineer (5+ yrs): real-time/streaming depth (WebRTC, voice, low-latency), plus infra and reliability ownership. Founding Product Engineer (2–4 yrs): frontend-leaning (React/Next.js), customer-facing, CS degree or equivalent standout shipped work. No need for a formal resume — just send a link to something you're proud of that real people used, and a line on what you owned. We read every one. → tarek@rivergtm.com