Answer by user6262626262 for Are HTTP headers case-sensitive?

The RFC for HTTP (as cited above) dictates that the headers are case-insensitive, however you will find that with certain browsers (I'm looking at you, IE) that capitalizing each of the words tends to be best:

Location: http://stackoverflow.comContent-Type: text/plain

vs

location: http://stackoverflow.comcontent-type: text/plain

This isn't "HTTP" standard, but just another one of the browser quirks, we as developers, have to think about.