Founding Full-Stack Engineer

18 hours ago

San Francisco, CA, United States Weekday AI Full time

This role is for one of the Weekday's clients

Salary range: $150K - $210K  & 0.50% - 1.00% equity
Experience: 1-4+ YoE

We are building self-improving software — AI that continuously creates and tests new in-app experiences. Our mission is to automate the end-to-end process of generating and experimenting with product flows, starting with onboarding for consumer apps and expanding to experiences across the user journey.

We work with some of the largest and fastest-growing consumer apps, already serving millions of users daily. Backed by top investors including Y Combinator, Gradient, and leaders from Uber, OpenAI, Meta, and more, we’ve raised over $5M to bring this vision to life.

Requirements

About the Role — Founding Full-Stack Engineer

As a Founding Full-Stack Engineer, you’ll be instrumental in designing, building, and scaling AI-driven products that reach millions of users. You’ll work directly with the founders, integrate cutting-edge AI models into real products, and own features end-to-end — from concept to deployment.

This is a full-time, in-person role based in San Francisco (Mon-Sat). US work authorization is required, but O-1 visa sponsorship is possible for exceptional candidates.

💼 What You’ll Do
  • Build an AI-powered paywall editor used by millions of users daily — from the Next.js front-end to a high-performance Python backend.
  • Integrate the latest AI models, APIs, and tools to enhance generation performance.
  • Write and deploy Python services capable of handling thousands of global requests per second.
  • Collaborate closely with founders and customers to design, implement, and deliver impactful features.
  • Wear multiple hats in a fast-paced, high-ownership startup environment.
✅ What We’re Looking For
  • 1-4+ years of engineering experience with a strong track record of shipping real products.
  • Solid full-stack skills — comfortable working across backend (Python) and frontend (React/Next.js) codebases.
  • Strong problem-solving abilities — able to break down ambiguous problems into clear solutions.
  • Experience building user-facing products and working directly with customers.
  • Ability to own features end-to-end, from quick specs to testing and deployment.
  • Excellent cross-functional communication skills.
🌟 Bonus Points
  • Experience integrating ML/AI/LLMs into applications.
  • Background with design tools, chat experiences, or creative coding platforms.
  • Prior startup or founding team experience.
  • Mobile engineering expertise (Swift, Flutter, Expo).
⚠️ This Role May Not Be a Fit If
  • You need highly structured requirements and dislike ambiguity.
  • You prefer to work on only one part of the stack.
  • You have no experience with systems involving many moving parts.
🖥 Our Tech Stack
  • Frontend: Next.js (React/Typescript), Zustand, Tailwind/Shadcn
  • Backend: Python, Fly.io, Supabase
  • Mobile: Swift, Flutter, Expo
💡 Some of the Challenges You’ll Tackle
  • Reinforcement learning for personalization — dynamically optimizing prices, paywalls, and user experiences.
  • Automated A/B testing — systems that select and run new experiments based on analytics + AI code generation.
  • AI-driven editor — tools for rapidly creating and improving paywall experiences.
  • Billion-scale content serving — Python services handling thousands of QPS for millions of mobile devices.
  • Mobile webview optimization — creating native-like performance across multiple mobile stacks.

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