Software Engineer · Builder
You have an AI idea, a prototype, or a product that's stuck. I find what's blocking it and ship the fix — then explain every decision to your team and your investors.
Proof, not adjectives
A live medical AI app, shipped for an international medical conference.
Next.js · FHIR · GPT-4
Zero to production, end-to-end.
full event-sourced backend
Cut a client's monthly cloud bill. Zero downtime.
cloud · storage migration
Test suite: 10 minutes → 30 seconds.
CI · static analysis
Code shipped in an open-source library other developers build on.
performance · open source
3+ yrs · AWS Certified · CS50 (Harvard) · open source contributor
What I actually do
I find what's costing you — and I cut it.
The AI prototype that won't scale. The architecture nobody wants to touch. The feature stuck in review for three sprints. I take the expensive problem everyone learned to live with — and I cut it.
Selected work
-
Clinical-decision-support AI chatbot
- Next.js
- Vercel AI SDK
- GPT-4
- FHIR
Built the full frontend for a HIPAA-compliant medical AI chatbot — voice input, tool-calling, production-ready.
Shipped on time for an international medical conference.
-
AR spatial-intelligence platform (backend)
- Laravel
- PHP
- Azure
- CI
Owned backend reliability: cut test time, migrated cloud storage, rolled out static analysis.
−95% test runtime · −70% infra cost · 200+ issues found.
-
AI travel-booking concierge
- Vue
- Nuxt
- AI SDK
- Gemini
Built an AI chatbot and real-time validation into the booking flow.
Higher conversion. Cleaner UX.
-
WordPress → Nuxt migration
- Vue
- Nuxt
- Feature flags
Migrated a WordPress-backed Vue app to standalone Nuxt, component by component, behind feature flags.
Zero data loss. Incremental delivery.
-
AI services marketing platform
- Next.js
- Playwright
- Atomic Design
Set up the project architecture and built visual regression testing with Playwright — accessibility in CI from day one.
Near-zero visual regressions · WCAG in CI.
Things I ship
My own products, in the wild.
Between contracts I build my own products and ship them. Not side projects — live apps, real users, running in production.
Wyszczaj.to
LiveWhere to pee in Poland.
A nationwide, community-driven map of public toilets and places to relieve yourself — find the nearest one, anywhere in Poland.
- Web
- Maps
- Geolocation
FramePicker
LiveThe perfect still from any video, picked by AI.
Drop in a video and let AI pull the sharpest, best-framed shots — turn a gym clip into a clean photo without scrubbing the timeline.
- AI
- Video
- Web
Who you'd be working with
I'm Karol — engineer and builder, based in Kraków. I take projects that are stuck or have no clear brief and ship them end-to-end. AI products, backends, performance work — whatever the problem actually is. I write down the why behind every decision, because in six months that reasoning is the only thing that saves you.
"I can confidently recommend Karol as a solid and dependable engineer."
How I work
What working with me looks like.
- 01
I own the outcome
Give me the problem, not a task list. I find the path, flag risks early, and ship — you don't chase me.
- 02
Remote, async, international
Contract, remote, worldwide. I work async-first with overlap for calls that matter. Decisions in writing, so your team isn't stuck waiting for me.
- 03
Two versions of every decision
Your engineers get the technical detail. Your investors get the business case. Same decision, two versions — no translation lost.
- 04
You're paying for the right call
Not hours. The right decision made once beats the wrong one made fast and unwound in three months. Rate and scope on the first call — no pitch, no surprises.
Let's talk
Have something that needs to ship?
Book a 30-min call. No pitch deck — just your problem and whether I'm the right person for it. Prefer email? I read everything myself.