Dennis Monner

Dennis Monner has served as Chief Executive Officer of Open Systems since October 2025, leading the company into its next phase of growth. As a serial entrepreneur, tech visionary, and internationally experienced CEO, he brings more than 25 years of leadership expertise in cybersecurity, cloud, and software-as-a-service.

With Gateprotect, he built one of the first German cybersecurity vendors to be recognized in the Gartner Magic Quadrant. He later founded Secucloud, which he successfully exited to Aryaka Networks. Following the acquisition, he joined Aryaka as Chief Commercial Officer. Under his leadership, the company expanded internationally and established itself as a relevant player in the SASE/XDR market.

Dennis has scaled multiple companies as CEO, CRO, and CCO across different growth stages — everything from ARR $100–250M to $0–30M and in between. He excels at combining technological excellence with entrepreneurial execution. He knows how to win in complex markets, scale global business models, and consistently put customer value at the center. His leadership style is defined by clarity, speed, and a relentless focus on empowering high-performing teams to drive growth and customer experience.

Beyond his role as CEO, Dennis is also an active investor and mentor in the European tech ecosystem. He brings extensive experience from working with private equity and venture capital firms and supports founders and executive teams in building internationally successful businesses.