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Conditional Requests & Concurrency

Last-Modified

IANA permanent response RFC 9110 2 spellings

Declared by 29 providers across 2002 published specification files in the APIs.io network.

What this header is for, and how to use it →

A count here is providers whose published contract declares this header — not providers who send it. Response headers set at the edge rarely appear in an OpenAPI at all, so a low number can measure documentation practice rather than deployment.

Spelled 2 ways

HTTP field names are case-insensitive (RFC 9110 §5.1), so every spelling below is the same header on the wire. A contract is not the wire: generated clients key off the string, and a developer reading two of these sees two different headers.

Last-Modifiedlast-modified

The registry

Statuspermanent
ReferenceRFC 9110, Section 8.8.2: HTTP Semantics

Providers declaring it (29)

airbus-oneatlas amazon-s3 an-api-of-ice-and-fire apache-ozone autodesk-fusion avito brightcove ccp-games cloudflare-r2 cubefs deliverect etsi eve-online honeycomb-io instabase lakefs lichess microsoft-azure newstore nhost oracle oracle-database puppet-labs salesforce viglink wikidata wikimedia wikipedia wso2

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