GB English, or US English?

As a Canadian, I run into this all the time. It's very difficult for me to type "color" as my muscle memory keeps reaching for the 'u'.

However, I tend to adopt the language of the libraries. Java has the Color class, so I use color.

I'd say look at how other libraries in your language choose and follow their convention.

The designers of the programming language and its built-in APIs made a choice, and whether the users are international or not they are used to seeing spellings consistent with this choice. You are not targeting speakers of a different language but users of a programming language. Odds are they've learned quite a few words in the foreign language from the built-in APIs, and they might not be aware there's differences between US English and GB English. Don't confuse them by switching sides of the pond.

I use .NET languages primarily, and the .NET Framework uses US English spellings. On this platform, I'd stick with US English. I'm not aware of any languages standardized on GB English, but if yours has done so then by all means stay consistent with the language.

Even though British English is what is spoken throughout the world - I recommend using American English which like other people have said dominate the market.

Definitely US english.

If you look back a few hundred years, you will find the change has nothing at all to do with the US, much as many would think so. The changes stem from European influences, particularly the French. Before that time, the English word "colour" was then actually spelt "color".

To try to standardise would be futile as half of Chinese children are learning the pre European influence and US understanding of English, while the other half are taking it up as it stands today, as the English language.

If you think language is a problem, then you should consider the Taiwan Kg which weighs in at 600g. I've yet to find out how they managed that one, but I hope they are never employed as aircraft fuelling personnel!