Senior Full-Stack Engineer, AI & Product

Rockstar is recruiting for a bootstrapped, profitable startup building the world’s leading nutrition app. The client helps people live healthier lives and achieve their fitness goals through a balanced diet. They are focused on scaling to eight-figure ARR while keeping the team small, nimble, and building innovative, AI-powered experiences.

About the Company

The company is building the world’s leading nutrition app, helping people to live a healthier life and achieve their fitness goals through a balanced diet. They are bootstrapped, profitable, building really cool AI-powered experiences, and focused on scaling to eight-figure ARR while keeping the team small and nimble.

The Role

The candidate will join a team of 6 engineers and contribute to projects across the stack. This is a dynamic opportunity where they will interface directly with the co-founders, design, marketing, and customers to build features that move the needle for the company and its community of highly engaged users.

The tech stack is fun!

- Frontend: Flutter

- Backend: fastapi (Python) + Go

- Databases: postgresql and mongodb

What You’ll Tackle

- Architect and scale the AI-driven "Nutrition Copilot" – The candidate will lead the development of an intelligent, multi-agent system that utilizes LLMs to provide real-time nutritional coaching. This includes building the conversational UI, implementing a robust Tool Manager for RAG against the food and user databases, and engineering the backend orchestration layer that handles complex tasks. It’s a really fun and ambitious project.

- Flutter development – Ship new features and maintain the existing codebase serving iOS, Android and Web, all written in Flutter and following atomic design with reusable components.

- Backend migration – Steer the migration from FastAPI to golang, starting with building a new backend for a brand new product offering. An exciting blank slate to make a mark.

- Automation – Explore and experiment with AI tools, custom-built internal software, and other automations to amplify the company’s effectiveness.

You’re a Fit If

- The candidate thrives in fast paced, nimble startup environments.

- They have experience with AI orchestration frameworks (e.g., LangChain, CrewAI, or building custom agentic logic).

- They have a strong understanding of RAG and optimizing LLM performance through tool-calling and prompt engineering.

- They have experience building high-concurrency backends to support real-time AI interactions and data streaming.

- They have a strong software engineering background, with at least 5 years of experience writing production code across frontend and backend.

- They have a demonstrable track record of shipping.

- They have an entrepreneurial mindset, whether they’ve created their own products, worked at startups, or have dreams to do so.

- They are hungry for impact and ownership, and they enjoy wearing multiple hats and learning new things.

- They consider themselves a generalist, not tied to any one technology, but excited to tackle new technical challenges.

- They have an appreciation and passion for great design, whether product, brand, or UI.

- They feel confident making decisions amid ambiguity.

Bonus Points

- The candidate has launched their own app, product, or other project.

- They have worked on subscription apps before, and words like “RevenueCat”, “paywall test”, and “MMP” mean something to them.

- They have some proficiency in design and feel comfortable tweaking Figma mockups and making design decisions when specs aren’t fully complete.

- They have integrated AI effectively into their workflows and are tuned into the latest AI tooling.

- They have worked on AI consumer products.

Why Join?

- Product-led. Both founders come from product management and engineering, each with 15 years of experience, so the candidate will be in good company.

- No bureaucracy. The candidate will be making top-level decisions alongside the founders every day.

- Maximum impact. The candidate will be taking the lead on an app with over 1 million downloads and 25,000 subscribers, and will help drive double or triple-digit % growth.

- High growth potential. The company is aiming for 10x (100x!) growth. The candidate will directly contribute to that.

- Positive mission. The goal is to improve people’s wellness through nutrition. The company hears stories every week of the life changing impact its product has had on the community’s health, confidence, sports performance, mental health, and overall wellbeing.

Compensation

- Competitive salary