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Mateusz K. TOP RATED

Penetration tester · OSCP
Kraków, Poland · Available now

About

Web and API penetration tests with clear, prioritised reports your developers can act on. OSCP, 7 years in offensive security, testing for fintech and health-tech companies.

Work history & reviews (13)

I will run a penetration test on your web application5.0

“Excellent communication and delivered ahead of schedule. Clean, well-documented work. Would hire again.”

Karim H. · Belgium · 27 Sept 2026
I will run a penetration test on your web application5.0

“Understood the problem quickly and proposed a better solution than we had in mind. Great experience.”

Erik J. · Finland · 10 Sept 2026
Web app penetration test5.0

“Solid work. A couple of small fixes were needed, handled quickly.”

Pierre L. · France · 8 Sept 2026
I will run a penetration test on your web application5.0

“Very professional. Clear milestones, honest estimates and quality work.”

Sofia L. · Sweden · 24 Aug 2026
Secure code review5.0

“Proactive and thorough — flagged issues before they became problems.”

Karim H. · Belgium · 14 Aug 2026
I will run a penetration test on your web application4.0

“Fast, reliable and easy to work with. The result exceeded our expectations.”

Pierre L. · France · 7 Aug 2026
API security assessment5.0

“Excellent communication and delivered ahead of schedule. Clean, well-documented work. Would hire again.”

Erik J. · Finland · 20 Jul 2026
Cloud configuration review5.0

“Understood the problem quickly and proposed a better solution than we had in mind. Great experience.”

Sofia L. · Sweden · 25 Jun 2026
Web app penetration test5.0

“Very professional. Clear milestones, honest estimates and quality work.”

Pierre L. · France · 31 May 2026
Secure code review4.0

“Fast, reliable and easy to work with. The result exceeded our expectations.”

Karim H. · Belgium · 6 May 2026
API security assessment5.0

“Great expertise and patience with our questions. Highly recommended.”

Erik J. · Finland · 11 Apr 2026
Cloud configuration review5.0

“Solid work. A couple of small fixes were needed, handled quickly.”

Sofia L. · Sweden · 17 Mar 2026
Web app penetration test5.0

“Proactive and thorough — flagged issues before they became problems.”

Pierre L. · France · 20 Feb 2026

Services by Mateusz

Employment

Penetration tester
Booking.com · 2017–2023

Education

Trinity College Dublin
MSc Computer Science · 2010–2012