Conway’s Law states that organizations develop systems that reflect their communication structures. Our study aims to test this hypothesis by analyzing the technical software architectures and correlating the software modularity with collaboration network characteristics. The collaboration network includes all interactions where two authors recently changed the same code. Higher-quality software architectures, plainly speaking, are more modular. They display a low complexity, and individual code unit sizes are small. Our regression models show a strong link between network and architectural modularity. We also demonstrate that an excessive concentration of expertise is associated with lower architectural quality. These findings support Conway’s Law and suggest that enhancing modularity in organizational structures may improve technical architecture by separating concerns into modules, thus informing the work of Enterprise Architects who produce their technical architectures in-house. Moreover, it aligns with the idea of agility, where modular teams work autonomously on specific parts of the technical architecture.