What Happened to Cal.com?

Cal.com emerged in 2021 from a project initially known as Calendso, with a mission to provide open, accessible, and extensible scheduling infrastructure as an alternative to proprietary tools. Co-founded by Peer Richelsen and Bailey Pumfleet, the company quickly gained traction, attracting thousands of users and hundreds of companies, from solo entrepreneurs to government entities. Its open-source nature allowed for significant community contributions and rapid development, positioning it as a leader in the 'Open Scheduling' category.

The company secured substantial funding to fuel its growth. After an initial $7.4 million seed round in December 2021, led by OSS Capital, Cal.com raised a $25 million Series A round on April 15, 2022, with Seven Seven Six and Obvious Ventures among the key investors, bringing its total funding to $32.4 million. This capital was intended to empower developers and expand its 'App Store for Time,' aiming to become the go-to platform for anything time-related, from productivity apps to telehealth solutions.

Throughout 2024 and 2025, Cal.com continued to innovate, releasing numerous product updates, including Cal.com v4.0 in April 2024, which introduced the Cal.com Platform and Cal Atoms. The platform focused on enhancing features like routing forms, round-robin scheduling, collective events, and team workflows, catering to diverse business needs and emphasizing automation and integrations. By early 2026, Cal.com was actively releasing versions like v6.1, v6.2, and v6.3, introducing features such as Cal.com Companion, a new bookings page look, and Cal.com Agents.

A pivotal moment arrived on April 15, 2026, when Cal.com announced a significant shift in its core strategy: moving its commercial production codebase from an open-source to a closed-source model. This decision was driven by escalating security concerns, specifically the rise of AI models like Anthropic's Mythos, which demonstrated an ability to rapidly identify vulnerabilities in publicly available code. CEO Bailey Pumfleet stated, "Open source code is basically like handing out the blueprint to a bank vault," highlighting the increased risk of AI-driven attacks. The company emphasized its commitment to protecting sensitive user data, prioritizing security over its open-source roots for its commercial offerings.

In parallel with this change, Cal.com launched 'Cal.diy,' a separate, fully open-source version of its platform under the MIT License, intended for hobbyists and developers to experiment with the software without impacting the production system that handles customer data. This move reflects a broader industry discussion about the future of commercial open source in an AI-dominated security landscape. As of April 15, 2026, Cal.com continues to operate as a leading scheduling platform, with its commercial product now closed source, while maintaining an open-source community edition.