I have yet to see a grammar/usage/style parser that’s better than my own training and experience. Certainly not one that I would, say, recommend to an undergraduate writer. Spell-checker, yes, though always with the caveat that autocorrect is not to be relied on.
The AP Stylebook isn’t the only authority. In fact, it’s not so much an authority as a house-style handbook, and any publishing writer needs to be prepared to follow whatever standards a particular outlet prefers. I routinely use “e-mail” because I’m old enough to have the old hyphenation conventions ingrained, but if an editor wants AP style, then that’s what I use.
