@Business,
Sorry, Business... as English is my first language, I am not very familiar with translation websites for English (I do have a second language, but it is not English).
I do think that people here are capable and nice enough to help with business English as well. If you post a question, you will sometimes get answers from professional writers, and if you post a paragraph, people who are very good at business writing (and there are many of us here) will likely critique or correct it for you.
There is a problem with asking native English speakers for translation websites. Since we don't need them, we have any reason to know about them.