Senior AI Product Engineer

Senior AI Product Engineer

About Fonzi AI

We're a Series A startup backed by Lightspeed revolutionizing hiring through AI. Founded by repeat entrepreneurs (Kumospace), we launched our AI-powered recruiting marketplace in June 2025 and are already revenue-positive with just under 100 employer partners—75%+ are AI-native companies. Thousands of engineers are on our platform, and we're running Match Days every two weeks where pre-screened candidates receive competing offers from top employers.

Our vision: build the infrastructure where AI learns what engineers actually do, what they want, and matches them to opportunities automatically. We're not just using AI at the edges—we're building toward a future where intelligent systems handle the entire recruiting workflow, and we need engineers who want to build that future with us.

The Role

The Senior AI Product Engineer is a new kind of role for a new era of software development. The line between "full-stack engineer" and "AI engineer" is blurring fast—and at Fonzi, we've stopped pretending it exists.

You'll own features end-to-end: from database schemas to React components to the AI agents that make our platform intelligent. Some weeks you're building robust backend systems. Other weeks you're experimenting with the latest models to create features that feel like magic. Most weeks, it's both.

We're looking for engineers who've had the "aha moment"—who understand that AI changes everything about how software gets built—and who want to work at a company where that belief is baked into every product decision.

What You'll Build

AI agents that conduct intelligent conversations with candidates—voice interfaces that onboard engineers, coaching systems that prep them for interviews, matching algorithms that learn from every interaction

The platform that powers a two-sided marketplace—TypeScript/Node.js backends, React/Next.js frontends, PostgreSQL data layer, all built for speed and iteration

AI-powered features from concept to production—rapidly prototype with the latest models, make smart trade-offs between cost/quality/speed, then scale the winners to thousands of users

The intelligence layer that makes our marketplace smarter with every candidate conversation, every match, every hire—the data flywheel that will define our competitive advantage

Required Experience

TypeScript across the stack: Strong proficiency in TypeScript, Node.js, React, and Next.js—you'll move fluidly between backend and frontend

Production AI experience: You've shipped LLM-powered features to real users—whether that's agentic systems, conversational AI, intelligent automation, or integrating models into applications. We care that you've done it, not how deep you went.

Product engineering mindset: You care about user experience, not just technical implementation. You'll help define the "what" not just build the "how."

Database fluency: PostgreSQL experience—efficient queries, sensible schemas, understanding of how data flows through a system

Startup velocity: 5+ years of experience with meaningful time in fast-paced environments where you owned problems end-to-end

Ship-first mentality: You default to shipping and iterating. You're deliberate about trade-offs but allergic to over-engineering.

AI coding tool mastery: You're fluent with tools like Claude Code, Cursor, Copilot, or similar. You don't just use them—you've developed workflows that make you dramatically faster. You understand when to lean on AI assistance and when to think for yourself.

The AI Spectrum (We're Flexible)

We recognize that "AI Engineer" means different things to different people. You might be:

A full-stack engineer who's been going deep on AI for the past year and wants to do more

An AI-focused engineer who can also build solid product features

Someone who's been building agentic systems and wants to apply that to a real business problem

A product engineer who uses AI tools daily and wants to build AI features, not just use them

All of these profiles can succeed here. What matters is that you can build across the stack AND have genuine experience shipping AI to production. The ratio is less important than the capability.

Nice to Have

Voice AI or conversational interface experience

Experience with agentic systems, AI orchestration, or Temporal.io

Background in marketplace, recruiting, or HR technology

Serverless architecture and GCP experience

Python for AI/ML tooling

You've created custom Skills, rules, or workflows for Claude Code, Cursor, or similar tools—you don't just use AI coding assistants, you extend them

What Makes You Successful Here

Extreme ownership: You take projects and run. Our tech lead wants to hand off entire features, not provide ongoing support.

Adaptability: Comfortable with rapid pivots, killing work mid-stream, and FIFO priority shifts. We move fast and directions change.

Direct communication: You flag issues early, propose changes proactively, and translate technical concepts for non-technical teammates.

Business instincts: You understand how your code impacts revenue and user experience. You make trade-offs accordingly.

What Makes This Special

AI playground: We're testing every model available. Constant experimentation. Freedom to build and break things.

Real users, real feedback: Thousands of engineers on the platform. Your code ships and you see impact immediately.

Ground floor timing: Early enough to shape architecture and culture. Established enough to have traction and resources.

No red tape: Flat structure, minimal documentation overhead, streamlined decisions. We optimize for speed.

Repeat founders: Leadership that's done this before. Sustainable pace. No theater.

Location

Brooklyn, NY (Williamsburg) — 3-4 days/week in office

Compensation

$175,000 - $225,000 base + meaningful equity