I see this question but I am going to make mine a little different.
I really like the quality of Google Docs spell check. I have a program which outputs near misses and I test some of these near misses and Google Docs beats everything I have seen hands down.
Therefore, within everything Google has to offer, paid or free-tier, is there any (legitimate) way to access Google's spelling capabilities? If I could download their dictionary, I still don't think is good enough, because it would not contain the context portion.