"S3-compatible" is one of those phrases that gets thrown around so much that people nod along without checking whether everyone means the same thing. Here's what it actually means, why it became the de facto standard, and what changes when you pick one implementation over another.
What "S3-Compatible" Actually Means
S3 compatibility means implementing Amazon's S3 REST API as a protocol — not as an AWS service you pay for. Specifically, it means supporting:
The shared data model:
Bucket — A flat namespace container (user-uploads, backups)
