Data & schema semantics · Validation & constraints

x-last-validated

`x-last-validated` appears in the info block. Its value is a string. Used by 26 providers across 80 OpenAPI documents. Observed values include `2026-08-30`, `2026-04-18`, `2026-05-30`, `2026-05-29`. Consistent with validation & constraints — this is inferred from where the key appears and what it carries, not from any published definition.

Data & schema semantics derived description

How this description was produced. It is assembled from what was measured in the corpus — where this key appears in a document, what shape its value takes, the values observed, and how many providers use it. It is not taken from a published definition, because for most extensions none exists. Read it as evidence, not as a specification. If you own this extension and want it described properly, tell us.

80 occurrences

80 documents

26 providers

purpose-named

Where it appears

Location in the document	Occurrences
info	80

What its value looks like

Value shape	Occurrences
string	80

Observed values

Sampled from the specifications, most frequent first.

2026-08-302026-04-182026-05-302026-05-292026-05-032026-05-282026-06-032026-04-19

Providers publishing it

All 26.

0x adobe-analytics agrio authentik blockchain.com dynatrace etsy frankfurter game-of-thrones google-places hypixel mindbody new-relic punkapi slice spoonacular tock tvdb ucsb virustotal wayfair weather-gov weatherapi wordnik yugabyte zoominfo

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 data & schema semantics job.