As Neptune’s first founding engineer, you will architect and build the core AI engine and product experience from the ground up. You’ll work alongside world-class founders to turn emotionally charged financial decisions into seamless, trust-based workflows. This high-impact role involves setting the technical foundation while shipping features that directly influence how couples build wealth.
Founding Engineer (Full Stack) at Neptune
Join Neptune as our first founding engineer to build the "shared brain" for couples navigating life's most consequential financial and legal decisions. Backed by $7.5M from Floodgate and The General Partnership, we're led by founders from Stripe, Google, and Uber. You'll own the product end-to-end, leveraging conversational AI and LLMs to turn complex, emotionally fraught workflows into empowering experiences. If you're an AI-native full-stack engineer with 4-7 years of experience and a desire to set the technical foundation for a category-defining fintech, we want to talk.
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Location
New York, United States
Compensation
$150k-$225k + Equity
Company
Neptune
Role overview
Neptune is building the concierge couples trust to navigate the biggest decisions of a life together. We pair emotionally intelligent AI with vetted legal and financial experts and transparent pricing, so both partners can make confident, fair decisions together and build a life - and lasting wealth - as a team.
At the center is a shared AI brain for couples that remembers everything for you, so you never repeat yourself and every next decision starts from what we already know. Couples make billions of dollars in financial and legal decisions over a life together, and no one has built the trusted companion that carries the full picture across all of them. That’s the category we’re defining, and it’s a rare moment to help build it from the ground up.
What you will do
- Design and ship the “Neptune brain,” a shared context engine that manages a couple’s full financial and legal history.
- Develop conversational AI and LLM-powered workflows that translate complex model outputs into high-credibility user experiences.
- Own features end-to-end across the stack, from backend architecture and Plaid integrations to frontend execution in Next.js.
Who this is a fit for
- Has 4–7 years of full-stack experience with a track record of shipping impactful production features in high-trust environments.
- Demonstrates deep “AI-native” intuition, using LLMs as force multipliers and understanding their performance across sensitive financial tasks.
- Possesses early-stage startup DNA, characterized by extreme agency, product-thinking, and the ability to thrive in an in-office NYC environment.
Why this role is remarkable
- Join a world-class founding team including the creator of Google Forms and the founding engineer of Stripe Link.
- Build a category-defining product backed by $7.5M from top-tier investors like Floodgate (early backers of Lyft, X, and Twitch).
- Gain massive ownership and founding-level equity while working with cutting-edge LLMs on high-trust, real-world financial and legal use cases.
How Jack & Jill work together
I get to know what you’re great at, then find roles you’d never find yourself.Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.
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If your profile’s a match and Neptune wants to meet, Jill will make the intro. In the meantime, Jack will send you excellent alternatives.