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HackDefense understands how hackers work. And gives you insight into your exposure.


We love to understand modern digital technology down to the smallest details. We genuinely enjoy deciphering the code behind cyber attacks.


HackDefense provides insight into complex technical subjects for those responsible for IT Security, whether they have an IT background or not. We understand how it works, and we exist to communicate our knowledge to you in a way that helps you understand how to act.

Our team.

We’re a team of Ethical Hackers, penetration testers and developers, with experience since 1999 and knowledge of the latest hacking techniques.

That’s how we can recommend strategic and tactical initiatives to counter hacking attacks, as well as do technical deep-dives with your system administrators and developers.

Our highly-educated and certified Ethical Hackers find security weaknesses. And tell you, clearly and concisely, what that means for you and your organization.

Mark Koek

Founder & CEO

Jacqueline Quist

Director Operations

Jony Schats

Red Team Lead / Principal Ethical Hacker / Security Officer / eCPTX / OSCP / PACES / CRTO / CRTE / CRTP / CESP / PNPT / eCPPT / eWPT / CARTP / AZ-500 / AZ-900 / SC-900 / OASP / CGCRTS

Thijmen Kooy

Service Team Lead / Senior Ethical Hacker / IT Security Advisor / OSCP / eWPT / CRTP / CRTE / CARTP / OSEP / OSWP / CESP / OSED

Niels Eriş

Pentest Team Lead / Principal Ethical Hacker / OSCP / OSEP / OSED / OSWP / eWPT / CRTP / CRTE / CESP / CARTP / AZ-900

Niels van Gijzen

Senior Ethical Hacker / Software Developer / IT Security Advisor / OSCP / eWPT

Jim Mak

Dev Team Lead / Ethical Hacker / Senior Software Developer / eWPT

Ronald Brand

Trainee Software Developer

Erik Japing

Ethical Hacker / Software Developer / eWPT / PNPT

Martin Hulsbosch

Ethical Hacker / PNPT / eWPT

Mike Oude Reimer

Ethical Hacker / CRTO / OSCP / CRTP / eWPT / eCPPT/ AZ-900 / CRTE

Bram Valstar

Software Developer

Wouter Werker

Sam Tieman

Intern / Assistant security tester

Mikey Heinrici


Yannik Marchand

Junior Ethical Hacker

Would you like to be part of this great team?

Are you a pretty good ethical hacker, if you say so yourself, or are you graduating and would you like to become an ethical hacker? HackDefense would love to talk to you.

Check our job openings