Marcin Kleczynski

Marcin Kleczynski was born November 1, 1989, in Łódź, Poland, and immigrated to the United States at age three. He grew up in the Chicago area, attending Fenton High School in Bensenville, Illinois, and worked as a computer-repair technician while teaching himself to write software tools in Visual Basic. After a stubborn malware infection on his family's computer, he built his own removal tool as a teenager — the seed of what would become Malwarebytes. He earned a B.S. in Computer Science from the University of Illinois in 2012, having built and run the company from his dorm room; by his late teens the business was already generating hundreds of thousands of dollars in revenue.

Kleczynski formally launched Malwarebytes with Bruce Harrison on January 21, 2008, growing it from a free remediation scanner into a global cybersecurity company. Notable milestones include a $30 million investment from Highland Capital Partners in 2014 and a $50 million round led by Fidelity Management and Research Company in January 2016, alongside relocating the company's headquarters to Santa Clara, California, in 2015. Over roughly two decades he has scaled the product to hundreds of millions of computers cleaned and near-billion download volumes, and today also serves as CEO of ThreatDown, Malwarebytes' business-focused brand.

He has been widely recognized as a young entrepreneur: Forbes "30 Under 30" Rising Stars of Enterprise Technology (2015), Silicon Valley Business Journal's 40 Under 40 (2014), and the Ernst & Young Entrepreneur of the Year Award (2014). Beyond company-building, he has been a philanthropic and civic supporter of the Electronic Frontier Foundation and the Tech Museum of Innovation in San Jose, reflecting a stated belief that "a secure digital life is a human right regardless of who you are or the size of your wallet."

• Invests personally as an angel, concentrated in areas adjacent to his own operating expertise: cybersecurity, network and bot security, and technical B2B/SaaS software.
• Backs early-stage, founder-led companies — he has both led seed rounds (Rithmio) and joined later growth financings (Netacea's Series A), indicating flexibility on stage.
• Draws on a hands-on operator's perspective: as a founder who built product before raising outside capital, he tends to favor teams with genuine technical depth and a real problem they've personally experienced.
• Emphasizes mission and impact in his public philosophy ("a secure digital life is a human right"), which aligns with security- and infrastructure-oriented bets.