The Deep Dive explores Serendipity, a PHP-powered open-source web blog engine, highlighting its strengths as a secure, extensible, and powerful alternative, particularly for beginners. Despite its tagline “not mainstream since 2002,” Serendipity is presented not as outdated, but as a stable platform grounded in core values of reliability and security, intentionally avoiding the trend-chasing of dominant players. It caters to two audiences: casual bloggers with its simple default setup and professional applications through its expandable framework architecture. Key guiding principles include reliability, with user input shaping the project; security, addressed proactively by the development team; ease of use, featuring understandable interfaces and developer-friendly code; and extensibility, allowing seamless growth via plugins and themes. Out-of-the-box, users receive an integrated editor, media library, and anti-spam measures, with tools for organization and user management. The platform’s extensibility is unlocked through its plugin system, managed via the Spartacus repository, enabling features like static page creation, transforming Serendipity into a small CMS. Technical requirements are standard (PHP 8.0+, various databases, web server), and while ImageMagick can enhance image processing, it’s not essential for basic installation. As an open-source project with a permissive BSD 3-clause license, Serendipity offers users maximum freedom to modify, build upon, and even commercialize applications without code sharing obligations. Its recent release (2.5.0 in Feb 2024) and healthy GitHub activity (220 stars, 92 forks) signal a living, evolving ecosystem. Serendipity offers a stable, user-driven, and flexible foundation for specialized, long-term online projects, supported by experts like Safeserver for hosting solutions.