Hi, I'm Przemek.
Lublin, PL · remote · since 2019
Websites, apps and automations, built by someone who knows how they get broken.
Development and security testing from one person. Usually that takes two vendors, and the gaps show up between them.
Available for new projects · replies within 24h
Services
$ build
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Websites and apps
Company websites, landing pages and web applications.
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SEO and GEO
Visibility in Google and in AI answers like ChatGPT.
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Automation
Workflows that connect your tools and remove manual work.
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Web scraping
Reliable data extraction, including from sites that resist it.
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Maintenance
Hosting and updates after launch, so everything keeps running.
# break
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Penetration testing
Web applications and APIs, tested before attackers get the chance.
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AI and LLM security
Chatbots and AI agents, tested for prompt injection and data leaks.
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Telecom network testing
Communication networks, where standard tools don't reach.
Selected work
- web
E-learning platform
launchingOne-on-one online lessons, matching students with tutors.
Stack: Next.js, NestJS, PostgreSQL, TypeScript, Prisma, Redis, BullMQ, Excalidraw, MinIO, Docker
- web
University timetable app
Class schedules that students check every day.
Stack: Next.js, Python, Flask, TypeScript, pandas, openpyxl, Selenium, MongoDB, Web Push, Docker
- automation
Telegram CRM
Contact and sales management inside Telegram.
Stack: Go, Next.js, PostgreSQL, MTProto, NATS, WebSockets, Prisma, Redis, Docker
- scraping
Sneaker release automation
Automated checkout across many accounts in parallel.
Stack: Python, zendriver, Playwright, nodriver, curl_cffi, Docker
- security
Banking and AI security audits
Penetration tests for companies in Poland and abroad.
Stack: Burp Suite, Python, OWASP Top 10, OWASP LLM Top 10, Faraday
FAQ
What services do you offer?
Web and app development, automation, web scraping, and penetration testing of web and AI applications. Based in Lublin, Poland, working remotely since 2019.
Why combine development and security?
Many security problems start in the handoff between the team that builds and the team that tests. Doing both makes security part of the build from day one.
Do you test AI chatbots and LLM apps?
Yes. Chatbots, RAG assistants and AI agents, checked for prompt injection, system prompt and data leaks, and unsafe tool use. The methodology follows the OWASP Top 10 for LLM Applications.
Do you work with clients outside Poland?
Yes. Projects run remotely for clients in Poland and abroad, in English or Polish.
How does a project start?
With an email to przemyslaw@raczynski.dev. Replies usually come the same day, and the first conversation is free.
Contact
Have a project in mind, or an app that needs testing? Let's talk.