Although I live in Australia, I'm very experienced in using US, NZ and UK English as well.
There's not much I haven't done.
Written articles, eBooks, blog posts, website content, resumes, etc.
Edited and proofread all of the above types of work.
I'm very flexible as long as the job isn't using technical jargon.
Having more than 100 testimonials tells me I must be doing something right.