You can't. At some point, you have to actually make use of the headers, and some of those uses require decoding to a string. There is some wiggle room here, suc

You can't. At some point, you have to actually make use of the headers, and some of those uses require decoding to a string. There is some wiggle room here, such as doing things like, header_as_raw_bytes == b"chunked" which I would argue is still decoding the header: your language of choice had to encode that string into bytes in some encoding in the first place, so even though you're comparing the encoded forms, there's still a character encoding at work. But, some of the headers are case-insensitive. E.g., Content-Type, Accept, Expect, etc. That golang bug is precisely not treating the non-characters (the "opaque octets", as defined by the standard, that is, the octets that form obs-text) as if they were characters. You won't hit that bug in the safe subset, presuming you're implementing other parts of the standard correctly. (Which is… a huge assumption, given HTTP's complexity, but that's sort of the point here.)