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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 / Senior Ethical Hacker / IT Security Advisor

Jacqueline Quist

Director Operations

Jony Schats

Senior Ethical Hacker / IT Security Advisor / Security Officer / eCPTX / OSCP / PACES / CRTO / CRTE / CRTP / CESP / PNPT / eCPPT / eWPT / CARTP / AZ-500 / AZ-900 / SC-900 / OASP / CGCRTS

Sander Meijering

Senior Ethical Hacker / IT Security Advisor / OSWE / OSCP /eWPTX / eWPT / eMAPT / CARTP / CAWASP

Thijmen Kooy

Senior Ethical Hacker / IT Security Advisor / OSCP / eWPT / CRTP / CRTE / CARTP / OSEP

Niels Eriş

Senior Ethical Hacker / IT Security Advisor / OSCP / OSEP / OSWP / eWPT / CRTP / CRTE / CESP / CARTP / AZ-900

Niels van Gijzen

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

Jim Mak

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

Baran Gecener


Bram Valstar

Software Developer

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