The “rumor” I know is that Amazon internally had a system broadly similar to S3/EC2, where a centralized infrastructure team made hardware resources available t

The “rumor” I know is that Amazon internally had a system broadly similar to S3/EC2, where a centralized infrastructure team made hardware resources available to the other teams through API. Then Amazon realized that they could use a similar system with external customers. They built S3 and other services in a way similar to their internal infrastructure, but completely separate. Only years later Amazon started using AWS for their internal services.