The AWS API has become infrastructure's common language, and a whole ecosystem has grown up around running it somewhere other than AWS. Some tools mock it for testing. Others implement it for real. Knowing which is which saves you from deploying a dev tool to production or wiring a production platform into your CI pipeline.
Two categories
The tools split into emulators and real cloud platforms. Emulators intercept AWS API calls and return plausible responses without provisioning real infrastructure, where state is usually ephemeral, VMs never boot, and the goal is behavioural approximation fast enough for a developer's inner loop. Real cloud platforms provision actual infrastructure where EC2 calls boot real virtual machines and block storage carries real persistence guarantees.
Emulators
Moto
