Founding Engineer

Neptune; New York (NY); On-site; USD 150,000 - 225,000; Full time

Benefits offered by this job

Base salary $150K–$225K

Founding equity 0.25%–0.75%

Ownership with CTO as engineering lead

Job summary

Neptune is seeking a founding Full-Stack Engineer to help build a shared operating system for couples, combining AI with vetted financial and legal workflows. You’ll be employee #1 on engineering and work directly with our CTO to shape product direction.

You will own features end-to-end, ship weekly to users, and contribute to a product that aims to earn deep trust from couples managing life decisions and wealth together.

Qualifications

• 3–6 years of full-stack experience.
• Track record of shipping features into production.
• Experience with AI/LLM-powered workflows is a plus.

Responsibilities

• Own features end-to-end (architecture, frontend, backend, deployment).
• Build the conversational AI and LLM-powered workflows at the heart of Neptune.
• Create the shared memory/context engine that remembers each couple's financial and legal life.

Skills

Full-stack engineer experience

Shipping features to production

AI integration

User-focused design

Tools

React

TypeScript

TanStack

Go

Job description

Neptune Founding Engineer (Full Stack)

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 operating system 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.

We (Ex-Stripe, Google, Palantir, Uber) have raised $7.5M from Floodgate (Lyft, X, Twitch) and The General Partnership, and demand is growing fast. We're hiring our first founding engineer to build the product every couple will trust with their most important decisions.

What we offer

• Compensation: $150K-$225K base, plus meaningful founding-level equity (0.25%–0.75%).
• Real ownership: You're employee #1 on engineering working directly with our CTO. You'll own large parts of the product and the technical direction.
• Impactful work: Build with LLMs on a real use case with product-market fit, on a small team where your work ships and reaches users every week.

Why this role is hard (and worth doing)

You’ll be turning something emotionally fraught, legally complex, and deeply personal, a conversation most couples avoid entirely, into a product people actually trust and enjoy using. You’ll design conversational AI that handles sensitive financial and emotional context with care, wire LLMs into real legal and financial workflows, and make outputs that have to be not just correct but have high credibility and trust to act on.

You’ll own features end-to-end (architecture, frontend, backend, deployment), and your decisions will set the technical foundation for everything Neptune becomes.

What you’ll own

• The product, end to end. Design and ship experiences that make life's biggest financial and legal decisions feel accessible and empowering. You own features from architecture through deployment.
• AI at the core. Build the conversational AI and LLM-powered workflows that are the heart of Neptune. Turn model outputs into experiences couples can trust with real money.
• The Neptune brain. Build the shared memory and context engine at the heart of the product, the system that remembers each couple's full financial and legal life and makes every next decision smarter.

You’ll work directly with the founding team (former Google, Stripe, Palantir, Uber, Thirty Madison) and talk to real users every week, watching what you ship change how couples make their most consequential decisions. Work is organized around the problem it solves, not where it sits in the stack.

We should talk if you’re…

• An AI-native engineer. You use AI coding tools as a genuine force multiplier and you have real intuition for how foundation models perform across different tasks.
• A high-agency builder. You take initiative, drive projects to done, and adapt fast when priorities shift. You’ve built something real that people actually used or paid for.
• A full-stack engineer with 3–6 years of experience and a track record of shipping impactful features into production. You can architect a backend and craft a frontend, and you think in product (UX, user value, workflows).
• Comfortable with ambiguity and energized by hard problems in a high-trust domain.
• A clear communicator. You’ll talk directly with users to get feedback and make sure the product genuinely delights them.

Nice to have

• Experience with our stack: React, TypeScript, TanStack, Go. We care more that you ship well than that you’ve used exactly these.
• Familiarity with fintech / financial-data platforms.
• Prior founding engineer experience, or having taken large ownership in a startup environment.

How we work

• Ownership and autonomy: each project solves a concrete problem, and you own it end-to-end.
• User obsession: you’ll talk to users directly and build for what they actually need.
• Fast iteration: weekly check-ins, problems over process, and a bias toward shipping.

Location

New York City: we’re in the office together five days a week.

How to apply

Email your resume to [e-mail].