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Since when are they case sensitive? https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/... says otherwise.

It's possible for a server to treat them as case sensitive, but that seems like a bad idea.

HTTP/2, headers are not unique if they only differ by casing, but they must be encoded as lowercase.

   Just as in HTTP/1.x, header field names are strings of ASCII characters that are compared in a case-insensitive fashion. However, header field names MUST be converted to lowercase prior to their encoding in HTTP/2.  A request or response containing uppercase header field names MUST be treated as malformed (Section 8.1.2.6).[1]

HTTP/1.X, headers are insensitive to casing for reasons of comparison and encoding.

   Each header field consists of a name followed by a colon (":") and the field value. Field names are case-insensitive.[2]

So, if Sec-Fetch-Site is sensitive at all, it would be sec-fetch-site when sending via HTTP/2 and you're responsive for encoding/decoding.

[1]: https://datatracker.ietf.org/doc/html/rfc7540#section-8.1.2

[2]: https://datatracker.ietf.org/doc/html/rfc2616#section-4.2

thatwasunusual 3 months ago [ - ]

>> FYI, HTTP headers are case insensitive

> Since when are they case sensitive?

[...]

thomascountz 3 months ago [ - ]

Perhaps the OG comment was misread or confusion was caused by a typo and/or edit.

When I originally read it hours ago, I also read it as "...HTTP headers are case sensitive," (emphasis mine).

That said, there is one caveat regarding case sensitivity for headers encoded for HTTP/2.

jonway 3 months ago [ - ]

My primitive instincts lead me to believe that sometimes they end up being Case-Sensitive and Sometimes NoT! (depending on implementation)