The Content-Language HTTP header — representation metadata, RFC 9110, declared by 16 providers in the API Evangelist catalog.
Content-Language
Representation Metadata IANA permanent response reached by regulation 2 spellings
A reference entry. The registry facts and catalog measurements below are complete; the written guidance for this header has not been authored yet.
Content-Language is representation metadata — Headers describing the payload itself — its type, length, encoding, disposition, location.
The registry
Listed in the IANA HTTP Field Name Registry as a permanent entry. Defined in RFC 9110, Section 8.5: HTTP Semantics.
In the catalog
Declared by 16 providers across 4,207 published specification files in the API Evangelist catalog, where it appears as a response header — sent by the server.
It is spelled 2 different ways across those contracts — Content-Language, content-language. HTTP field names are case-insensitive (RFC 9110, §5.1), so every one of these is the same header. They are not the same string, which is why generated clients disagree about it.
Reached by regulation
Nothing requires this header. The connection is inferred — it would be good evidence, and no regulator has asked for it. It is observable at the edge: an unauthenticated request is enough to see whether a provider sends it.
Reached by these regulations
Catalogued at regulations.apievangelist.com, with the basis of each connection recorded rather than implied.
Governed by these rules
Machine-enforceable governance rules from rules.apievangelist.com that apply to this header when it appears in an OpenAPI.
OpenAPI Components Headers Error error
Utilizing the headers object in the centralized OpenAPI components library helps make headers reusable across API requests and responses
Guidance: Rate Limits →OpenAPI Components Headers Info info
Utilizing the headers object in the centralized OpenAPI components library helps make headers reusable across API requests and responses
Guidance: Rate Limits →OpenAPI Headers Hyphenated Pascal Case error
HTTP headers should follow Hyphenated-Pascal-Case naming convention for consistency and readability, such as Content-Type, X-Request-Id, or Accept-Language.
Guidance: Naming →