7 min read
Mateusz Muszarski
Full-stack product engineer
Code is only the tool. I build products that solve real problems and bring results.
- Solo, end to end
- Web + mobile
- Both app stores
Internship · Cetuspro · 2026
PstrykWeb
Bespoke websites for local businesses, ordered through one online form.
A local business owner answers a few questions in one online form and orders a website made for their business. I built PstrykWeb for Cetuspro, a Polish software house.
Live
Built with
- Next.js
- TypeScript
- Vercel
Own product · solo · 2026
Linkoglot
Snap a photo, get flashcards. A subscription language app, shipped solo to both stores.
Point the camera at a street, a room or your breakfast, and Linkoglot turns what it sees into flashcards and quizzes. Free to try, then a monthly or yearly plan; the app comes in 30 languages. I built and published it alone.
Live · pre-traction
Built with
- Expo
- React Native
- Supabase
- RevenueCat
- Lingui
Internship · Neoteric · 2026
Clockful
- 118 automated tests: 49 Vitest, 69 Playwright
- 5/5 tables behind row-level security
- 15 requirements in the spec
- 9 days from spec to hand-in (an estimate)
A role-based time tracker, built with AI agents under a deadline.
An internship brief from Neoteric, a Polish software house: a time tracker where employees log their hours and admins see the reports. The rule was to build it only with AI agents, against a deadline. I directed them and verified what they built, from the database rules to the tests.
Code private · no public deployment
Built with
- Next.js
- Supabase
- TanStack Query
- Vitest
- Playwright
Personal · solo · 2025
A portfolio you fly through: Earth to Neptune in 12 camera stops.
My previous portfolio: a scroll-driven flight through the solar system, where each planet holds one section. 13 shaders written by hand in GLSL. Best on a computer.
Built with
- three.js
- React Three Fiber
- GSAP
- Vite
Space folio
Also shipped
- Malatro Balatro, but every card is a real maths exam task. (opens in a new tab)
- yws.lu A 3D site for a Luxembourg non-profit that houses young people. (opens in a new tab)
Product engineer
Stop 01 · Client
I start with the person paying for it, and what they need to earn.
- goals in numbers
- budget
- deadline
Stop 02 · Users
Who uses it, what they want done, and where they give up.
- user flows
- real app references
- drop-off points
Stop 03 · Conversion
Fewer steps between interest and action.
- one clear CTA
- short forms
- fast pages
Stop 04 · Revenue
How it earns is designed in from day one.
- pricing
- payments
- RevenueCat
Stop 05 · Code
Then the code: web, mobile and backend, end to end, tested.
- TypeScript
- automated tests
- code review
Stop 06 · Ship
Shipping is part of the job: pipelines, deploys, store releases.
- GitLab CI/CD
- Vercel
- App Store and Google Play
- Search Console
Stop 07 · Measure
Measure, then decide what changes next.
- analytics
- Lighthouse
- user feedback
I run AI like a team.
I lead. Claude Code agents do the work, each with its own job, and nothing ships before I review it.
01 I brief the lead agent: the goal, the limits, what done looks like.
- goal
- limits
- definition of done
02 It reads the wiki the agents keep. A hook picks the pages this task needs.
- Karpathy-style LLM wiki
- routing hook
- decisions
- lessons
03 Subagents research in parallel and bring back conclusions.
- subagents
- docs
- references
- audits
04 MCP servers bring real data: real app screens, components, a browser.
- MCP
- Mobbin
- shadcn registry
- Playwright
05 It builds inside the rules. Hooks stop the risky moves.
- safety hooks
- scripts
06 Skills and gates check every change: types, tests, accessibility, speed.
- TypeScript
- ESLint
- Vitest
- axe
- Lighthouse
07 I review and decide. What we learned goes back into the wiki.
- code review
- lessons
Competences
-
- ZSE Starogard Gdański programmer technician, plus an IT technician course In progress
- Cetuspro remote, real commercial projects June 2026 – now
- Neoteric 6 weeks, building with AI agents 2026 · 6 weeks
- KS Beniaminek 03 soft skills and social projects 2025 · 1 month
4 years of steady improvement Since 2022 Since 2022: studying, freelancing solo, launching my own startups, internships, and building real-world products.
Details on the CV -
Polish state vocational exams (CKE / OKE) 2024 Websites, web applications and databases.
Details on the CV -
Course by Bruno Simon January 2025 90+ hours of WebGL, shaders and Blender: bringing 3D worlds to the web, taught by Bruno Simon, one of the best-known creative developers out there.
The course (opens in a new tab) Certificate (opens in a new tab) -
Courses by Jonas Schmedtmann, Udemy 2023 JavaScript and React from the fundamentals up: about 135 hours of video, lots of coding challenges and assignments, practice projects, and theory lessons on how things work under the hood.
Details on the CV -
Youth exchanges and volunteering 2024–2025 Youth exchanges, trainings and volunteering in Latvia, Lithuania, Georgia and Türkiye, with people from other countries, in English. In Demre I spent two months volunteering with the European Solidarity Corps for Caretta caretta sea turtles.
Details on the CV -
Team events 2026 A hard problem, a team and a clock. They teach me to decide fast, split the work and ship something that works under pressure.
Details on the CV -
Additional knowledge 2025 What experience and courses taught me about how people decide, buy and use products. It's why I think about users and conversions, not just about making the code compile.
Read: psychology in UX
Writing
Notes from the work
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Let's talk
A role, a project or a question. One line is fine.
- Full-time or contract
- Remote or hybrid · Poland, CET
- English · Polish
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