- According to W3’s “HTML and URLs” they should:
There may be URLs, or parts of URLs, where case doesn’t matter, but identifying these may not be easy. Users should always consider that URLs are case-sensitive.
- Domain names are case insensitive according to RFC 4343. The rest of URL is sent to the server via the GET method. This may be case sensitive or not.
- Depends on the hosting os. Sites that are hosted on Windows tend to be case insensitive as the underlying file system is case insensitive. Sites hosted on Unix type systems tend to be case sensitive as their underlying file systems are typically case sensitive. The host name part of the URL is always case insensitive, it’s the rest of the path that varies.