x-amz-signature
`x-amz-signature` appears on schema objects and properties. Its value is a string. Used by 9 providers across 10 OpenAPI documents. It sits in the `x-amz-` namespace, so its meaning is defined by amz tooling rather than by OpenAPI. Observed values include `string`, `6b715e441bd7ea5beec87f8415230a600be6dfd76b8f89103137618dca959fac`, `a249243213026c97ac80f9b2e4b2ef06c7c491022a8cf8e46f0ddf95a746e6f7`, `fcd6309a6aaee213348666a72abed8b44552a43acb6b340e8e1b288d21a5fe92`. Consistent with security — this is inferred from where the key appears and what it carries, not from any published definition.
Where it appears
| Location in the document | Occurrences | |
|---|---|---|
| schema | 20 | |
| response | 3 |
What its value looks like
| Value shape | Occurrences |
|---|---|
| string | 17 |
| object | 6 |
Observed values
Sampled from the specifications, most frequent first.
Providers publishing it
All 9.
Why this is not in OpenAPI
Extensions exist because a provider needed something the specification would not carry. Most of what they hold is not the API contract at all — it is operational metadata about the contract: documentation, lifecycle, policy, provenance, and now agents. That metadata is usually better placed alongside the contract, in an Overlay or an APIs.json index, than crammed inside it. See everything else doing the security job.