Cal.com Moves Commercial Software to Proprietary Licensing for Security Reasons

Thu, 16 Apr 2026 15:56:00 +0200

Cal.com, a company known for its scheduling software, announced that it is transitioning its main commercial product from open-source to a proprietary license. The decision is largely motivated by concerns that AI-assisted tools make it easier for attackers to find vulnerabilities in publicly available code, putting sensitive customer booking data at risk. Co-founder Peer Richelsen and CEO Bailey Pumfleet argued that open-source code is akin to providing a blueprint for a bank vault, and with AI, attackers can study these blueprints much more efficiently. While the commercial product will now be closed source, Cal.com continues to support open-source development by releasing Cal.diy, a version designed for hobbyists and experimentation. The move has sparked debate in the tech community, with some arguing that AI tools could also be used defensively to identify and fix vulnerabilities, while others see the change as an attempt to protect the company from additional work or competition.