This podcast interviews Andrew Firestone (CEO) and Knut Sveidqvist (CTO) of Mermaid Chart, a text-based diagramming software built from an open-source project. The discussion traces the origin story of Mermaid, its unexpected growth, and the subsequent creation of Mermaid Chart, highlighting the challenges and strategies of commercializing an open-source project. Key learnings include the importance of defining the line between open and closed-source features, leveraging the existing community for product development, and the strategic use of AI integration to expand the user base beyond software engineers. The founders discuss their partnership with OpenCore Ventures and the lessons learned in navigating the unique aspects of building a business around an established open-source community. The interview concludes with reflections on the hardest parts of their journey and advice for other founders considering similar paths.