How Block Unified 450 Code Repositories Into One

Block merged 450 code repositories into one to reduce development friction and speed up cross-team collaboration for its engineers.

Block has successfully consolidated approximately 450 individual Java-based code repositories into a single, unified monorepo. This major engineering initiative impacts developers across its Cash App and Square organizations. The primary motivation was to tackle "dependency drift," a common problem where different projects use mismatched versions of the same shared software libraries. This inconsistency created significant coordination challenges and slowed progress, as teams spent time resolving conflicts instead of building features. The new, centralized system is built for scale, now supporting around 8,800 builds each week while maintaining efficient performance.

The shift to a monorepo provides several key advantages. It dramatically simplifies making changes that affect multiple services, as developers can update all relevant code in one operation. This ensures consistency and eliminates the complex process of coordinating updates across dozens of separate repositories. To prevent the monorepo from becoming slow, Block invested in an intelligent build system. Its continuous integration (CI) pipeline uses a dependency graph to selectively test only the code impacted by a new change. This targeted approach keeps the vast majority of build times under 10 minutes, a critical factor for maintaining developer productivity. Custom tooling for code editors further enhances the developer experience by providing better visibility into the large codebase.

This case study offers a practical blueprint for other technology companies facing similar scaling challenges. As organizations grow, managing a sprawling landscape of microservices often leads to development bottlenecks. Block's experience demonstrates how a well-executed monorepo strategy, supported by custom tooling and selective CI, can improve build visibility and streamline cross-team collaboration. The project highlights the trade-off of moving complexity from repository coordination into a more sophisticated build system. For CTOs and engineering leaders, it serves as a valuable example of taming complexity at scale.