From
IANA permanent
request
RFC 9110
2 spellings
Declared by 5 providers across 21 published specification files in the APIs.io network.
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.
fromFrom
The registry
| Status | permanent |
|---|---|
| Reference | RFC 9110, Section 10.1.2: HTTP Semantics |
Providers declaring it (5)
bazaarvoice cisco-ise mailgun outdoorsy pagerduty
Explore
All headers Agent & Bot Identity 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.