Software Engineer (Mobile / Full Stack) — Founding Team at Happai

Location: Remote (U.S.)

Type: Full-time

Compensation: Competitive salary

About Happai

Happai is an early-stage tech startup on a mission to help people understand and improve their happiness through data. We’re building a beautifully designed, AI-powered app that tracks users’ daily emotional states, uncovers meaningful patterns, and delivers personalized insights to help people live with greater emotional well-being and self-awareness.

Our team combines deep expertise in entrepreneurship, product design, behavioral science, and marketing, with a proven track record of scaling (our founder built a $1 billion company). We’re now channeling that experience into creating a first-of-its-kind product that helps people uncover the habits and mindsets that truly drive happiness, using a proprietary framework to analyze daily life patterns.

Our early MVP has already generated a strong “wow” reaction from everyone who’s experienced it — and we’re just getting started.

What You’ll Do

You will have end-to-end ownership of building the MVP and shaping the product’s technical foundation. You’ll collaborate closely with the founder and designer to turn the MVP designs into a fully functional, polished app.

Your responsibilities will include:

• Building the first version of the Happai app (iOS, Android)
• Developing and integrating APIs (e.g., OpenAI, analytics, authentication, data storage)
• Architecting the backend (FastAPI, Firebase, or similar)
• Implementing a delightful, smooth user experience with data persistence
• Collaborating with design to refine animations, UI/UX, and onboarding flows
• Contributing to product direction, technology stack choices, and company culture.

Ideal Candidate

We’re looking for someone who’s not just an exceptional engineer, but also a creative builder — excited by the opportunity to craft an experience that changes how people understand themselves.

You might be a great fit if you:

• Have 3–7 years of experience in mobile app development (React Native, Flutter, SwiftUI, or Kotlin)
• Are fluent in backend integration (Python FastAPI, Node.js, Firebase, or Supabase)
• Have experience with AI/ML APIs (OpenAI, LangChain, etc.) or want to learn fast
• Are passionate about creating emotionally resonant, user-centric apps
• Have a solid grasp of data architecture, security, and privacy
• Value clean architecture, scalability, and intuitive UX
• Possess an entrepreneurial mindset: take ownership, set standards, and help build the team
• Thrive in a fast-moving, zero-bureaucracy startup environment.

Nice to Have:

• Experience in mental health, well-being, or regulated data environments
• Proven record of shipping 2+ consumer apps end-to-end.

Why Join Happai

• Be an early founding engineer with ownership and influence from day one
• Work directly with the founder
• Build a product that helps people live better, more self-aware lives
• Shape the culture and future direction of a company with massive potential
• Enjoy creative freedom and an environment that values deep work, learning, and joy.

How to Apply

Send a quick note (and links to your GitHub, portfolio, or apps you’ve built) to polina@happai.com or apply directly here on LinkedIn.