Stefan Simić

About

Building products end-to-end

I'm a software engineer with 6+ years of experience building products end-to-end - from mobile and web frontends to backend services and internal tooling. My core stack is JavaScript/TypeScript, working daily with React Native/Expo, React/Next.js, and Node.js, and I've taken products all the way from idea to production, including subscriptions and payments (Stripe, RevenueCat), analytics, and release management. What I bring to a team is ownership: I'm comfortable leading development, making pragmatic technical decisions, and shipping user-friendly, high-performance software that moves the business forward.

Experience

Where I've shipped

1. Head of Development - Younger Fitness

   Oct 2024 – Present

   • Lead end-to-end development of the Younger fitness platform, spanning the mobile app (React Native/Expo), website (Next.js), backend services (Node.js), and internal admin dashboard.
   • Design and deliver core product functionality across activity tracking, training experiences, onboarding, social, and gamification.
   • Own the monetization stack, including subscription and paywall infrastructure (RevenueCat), Stripe checkout flows, and affiliate and attribution integrations.
   • Drive marketing and analytics capabilities through integrations with Meta Conversions API, AppsFlyer, Klaviyo, and product analytics tools.
   • Ensure platform quality and stability through SDK upgrades, performance optimization, observability (Sentry, Clarity), and release management.
   • Build internal admin and analytics tooling supporting content management, user operations, and business insights.
2. Co-Founder - Navo

   Ongoing

   • Co-founded Navo and lead its product development, building the platform with React, Next.js, and Supabase.
3. Software Developer - Tangled Group, Inc

   Apr 2022 – Feb 2024

   • Developed software at a company specializing in traditional and generative AI OCR, delivering ML/AI solutions optimized for IoT and resource-limited devices.
   • Worked in the Engineering and Technical department building high-performance, production-grade applications.
4. Frontend Developer - DCLOUD

   Jun 2020 – Apr 2022

   • Implemented UIs using modern frameworks: React, Svelte, and Vue.js.
   • Created reusable, dynamic components and handled backend integration.
   • Worked with TypeScript, Tailwind CSS, Docker, Cypress (E2E), unit testing, and Agile workflows (Jira).

Skills

Tools I work with daily