Kacper Karpowicz.
Background
Film set
instincts.
Production
code.
I came to code through years on Polish film sets, recording production sound on feature films and primetime TV drama. Sets teach you a particular discipline: there are no second takes, the whole crew waits on you, and either it works or it doesn't.
That's the same instinct I bring to shipping software. Clean architecture. Optimistic UI. Performance that doesn't cave under real users. Things that actually work in production.
My recent work spans Vocabingo — a language learning app with spaced-repetition scheduling — a dual-strategy portfolio tracker with 120+ REST endpoints and market regime detection, content aggregation platforms, an automated trading bot running 24/7 on a Raspberry Pi, and bilingual commercial sites with custom calculators.
Most of my stack is self-taught through shipping real projects — not coursework. I'm open to ambitious work where I can own features end-to-end.
Selected work
Things
I've shipped.
Vocabingo Lang Applive ↗
Language learning app using spaced repetition. 10 words a day with intelligent review intervals, pause/resume sessions, catch-up mode, dark/light theming.
Najlah Vanslive ↗
Custom campervan conversion company in Kraków, 20+ completed builds. Interactive cost calculator with dynamic pricing, bilingual PL/EN, WooCommerce store, portfolio showcase and sticky CTA architecture.
Maëva Boche Portfoliolive ↗
Next.js 14 site for a French cinematographer. Image-focused snap-scroll layout, embedded Vimeo player, filterable project gallery, image modals, Framer Motion choreography, contact form via Resend.
Kwiat Cebulilive ↗
Content aggregation platform curating the best of Reddit, X and YouTube. Infinite scroll, search & filtering, Cloudinary media.
Yama Studio Warsawlive ↗
Recording studio site offering vocal recording, mixing and engineering services. Pricing, team, beats and publishing arm.
Psi-jaciel Shelterlive ↗
Polish non-profit animal shelter with adoption search, virtual adoption, 1.5% tax-redirect calculator and volunteer hub.
StrawberryFreshlive ↗
Aggregator with virtualized scrolling, dark mode, Cloudinary integration and SEO-first MongoDB architecture.
Portfolio Strategy Tracker
Local-first hybrid full-stack app for tracking two investment strategies. 120+ REST endpoints, real-time WebSocket market data, VIX-adjusted DCA, market regime detection, execution quality scoring vs VWAP, Monte Carlo simulations, PDF/CSV reports.
Trading 212 Mean-Reversion Bot
Production-ready automated trading bot on AAPL. RSI + SMA signals, 24/7 on a Raspberry Pi with systemd, state persistence, retry logic, rotating logs, paper-trading mode, pytest coverage.
bien sûr
Habit tracker on Next.js 16 and React 19. Calendar interface, streak tracking, optimistic UI updates, theme switching, Framer Motion micro-interactions.
YelpCamp!
Full-stack camping app with auth, full CRUD, ratings, comments and a RESTful API across the Express stack.
Functional React calculator using Hooks and props for clean data flow — modular, maintainable, modern practices.
Recursive converter that visualises the call stack as it executes, animating each step of the recursion.
Web music player with play/pause, navigation, shuffle and removal — all built on the JavaScript Audio object.
Two-player React game with dynamic board, move log, winner detection and restart. A small, complete React study.
Basic arithmetic with custom Webpack config. Bundles multiple dev files into two production files: HTML and JS.
RPG with combat system, player progression, enemy AI, XP/leveling mechanics, inventory, interactive environments.
Toolkit
The stack.
- TypeScript
- JavaScript (ES6+)
- Python
- PHP
- SQL · HTML · CSS
- React (Hooks, Redux)
- Next.js 14–16 · React 19
- Tailwind CSS
- shadcn/ui
- Framer Motion · Recharts
- Node.js · Express
- FastAPI
- REST · WebSockets
- PostgreSQL · MongoDB · SQLite
- Prisma · Mongoose
- WordPress · WooCommerce · ACF
- Vercel · Redis · Cloudinary
- Raspberry Pi · systemd
- GA · Search Console · GTM
- Figma · Photoshop · Illustrator
Experience
My working history.
Designed and delivered modern responsive sites end-to-end. Built reusable React component libraries with Hooks and Redux, and maintained custom WordPress themes with PHP, ACF and page builders. Collaborated with distributed teams of designers, analysts and developers.
Shipped responsive, accessible interfaces with designers and PMs. Built bespoke WordPress themes in PHP beyond plugin configuration, optimised for performance and SEO with structured data, and crafted animations and micro-interactions that lifted UX above static layouts.
Production sound on Polish feature films and primetime TV drama. Selected credits: Lalka (2025), Przyjaciółki (2024), Skołowani (2023), Stulecie Winnych (2022), Wotum Nieufności (2022), Bracia (2021).
MA Film (Sound), Screen Academy Scotland, 2019 · BA (Hons) English and Film, Edinburgh Napier University, 2018. Languages: Polish (native), English (C1), French (A2), Spanish (A1).