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Last-Modified

IANA permanent response RFC 9110 2 spellings

Declared by 43 providers across 2512 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

Status	permanent
Reference	RFC 9110, Section 8.8.2: HTTP Semantics

Providers declaring it (43)

acronis adp airbus-oneatlas amazon-s3 apache-ozone autodesk-fusion avito brightcove btc-war-live-market-data-api ccp-games cloudflare-r2 cubefs deliverect dotdigital eclipse etsi euronet eve-online game-of-thrones here honeycomb-io instabase lakefs lichess microsoft-azure microsoft-azure-batch nasuni newstore nhost oracle oracle-cloud oracle-database oracle-platforms qliksense salesforce sovrn stanford viglink wikidata wikimedia wikipedia wso2 zhejiang

Explore

All headers Conditional Requests & Concurrency Guidance on headers.apievangelist.com

Work with this as data

Every header here is available over the APIs.io API and to AI agents over MCP. HTTP Headers is not yet its own endpoint on the v1 API. Reach it through catalog search and the tag graph, or the MCP server.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for http headers

3 MCP tools reach this

apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
find_cohortsEvery scored population of providers in the catalog.

All 92 tools →

Call it yourself

curl for this page

Search the catalog

curl "https://apis.io/api/v1/search?q=last-modified&limit=10"

Everything under a tag

curl "https://apis.io/api/v1/tags/last-modified"

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