Learn to secure modular monoliths through an entertaining analogy comparing software architecture to cat care in this 40-minute conference talk. Discover how cats and modular monoliths both require attentive care, consistent boundaries, and secure environments, while exploring the security challenges that emerge when scaling modules beyond the monolith's boundaries. Examine key security concerns specific to modular monolith architectures and implement practical solutions that prevent security disasters during system scaling. Gain insights into planning security measures upfront to ensure smooth transitions from monolithic to distributed architectures, all while enjoying humorous comparisons between software development and pet ownership that make complex security concepts accessible to developers regardless of their pet preferences.