Open-source software has finally come of age and is reshaping the entire software industry as we know it. The proprietary software industry is being eaten into by open-source, with multi-billion dollar exits in recent years, including $4 billion to $7.5 billion, with two in the last week alone. Given this trend, everyone in the industry should be closely watching why open source is flourishing today and what it means for the future of the software industry. Open-source technologies are beating proprietary software in terms of quality, cost, and scalability. The open-source model is not just free but also provides a community-driven approach to software development, which leads to higher-quality code, eliminates vendor lock-in, and helps with hiring and personal development. However, developing successful open-source projects is challenging due to balancing openness with sustainability and managing the transition to the cloud. While some applications are well-suited for the open-source model, others may not be. The future of software is open, and unless proprietary software businesses adapt, they will lose.