A writer/editor colleague and friend asked me for my opinion on Grammarly, which is under discussion on the Quora forum. Here is my take on it:
"As with most other spell, style, and grammar checkers, this program is only as good as the humans who input the content and coded it, which is to say that it does some good but also some harm. As an added layer of quality control, as a backup, as a second pair of eyes, it’s probably somewhat useful, especially for a non-writer or novice, but there really is no substitute for a real human editor. The main problem with all such word programs is their occasionally vague or unhelpful or downright silly suggestions. Their best calls are probably outright spelling errors and duplicated words, so it wouldn’t hurt to run those tests just in case you were sleepy or impaired when you wrote the copy."