Some of the international use might be because the United Nations uses Oxford spelling [1]. My employer does too.
GNU Aspell has several variants of "British English", including "British English (United Kingdom) [-ize suffixes and with accents]". KDE seems to use the same dictionary, so in KDE applications I have full support for "Oxford spelling".
There's a Firefox extension which includes -ize endings, but also includes -ise endings, so it's less useful.
Not all of the ise/ize endings are interchangable, so the Firefox extension might be correct. -ize is only applicable for words with a Greek root, I believe, which is why choosing Oxford English was hardly a masterstroke on my part but it does make things more interesting.
I have little experience of Aspell short of seeing it pop up as a dependency now and then, but I will now try and attempt incorporating it into my Mac's dictionary, ideally it would work on iOS as well.
I have little experience of Aspell short of seeing it pop up as a dependency now and then, but I will now try and attempt incorporating it into my Mac's dictionary, ideally it would work on iOS as well.