Jeff Bezos's 'API Mandate'

Jeff Bezos issued a company-wide mandate that all internal teams communicate solely through well-defined APIs, with no direct calls or data access to another team's storage. This forced a modular, service-oriented architecture.

Significance

This mandate was the philosophical and architectural precursor to Amazon Web Services. It forced Amazon's engineers to build the decoupled, scalable services (like messaging queues) that would eventually be offered publicly.