For those who don’t want to read a long review, here’s the brief summary: The free version of Grammarly is a useful utility for writers, but only if they already have a good knowledge of English grammar.
Grammarly is an English language grammar checker. It is available as a browser extension, an MS Word add-on, or as a standalone application. It is seemingly free but promptly starts urging you to upgrade to the premium (subscription) version. They offer a 7-day money-back guarantee on subscriptions, but I found so many people complaining about it not being honored (and poor customer service in general) that I opted to only test the free version.
I installed the macOS version. To test it, I employed the text from my 160,000+ word first novel. I pasted each scene individually into Grammarly, and it then proceeded to analyze the text and flag issues. The issues are divided into critical and advanced categories, with the advanced requiring the premium version. Critical issues are flagged to the right of the line of text where they were found. There are options to accept (and apply) the recommended change, to view more information, or to simply ignore it. An example issue is to flag “afterwards” and suggest a change to “afterward”.
So how did Grammarly do? It did an excellent job of spotting repeated words and mistakes such as writing “though” when you meant “through”. These kinds of errors are the ones that our brains often skip right over without us even noticing. It also did a good job of recognizing when commas were either omitted or unnecessary. Unfortunately, that’s pretty much the complete list of things Grammarly does well.
Grammarly will often recommend changing a verb from singular to plural or vice versa. It is occasionally correct, but often wrong. It will also make suggestions when it thinks you have typed the wrong word by mistake, but most of these are wildly wrong. For example, it repeatedly suggested replacing “robe” with “role”. This is the kind of mistake no human proofreader would ever make.
I also experienced problems employing the Grammarly application. Sometimes when I pasted in new text it would fail to scan it, forcing me to start a new document. Sometimes the scan would get stuck and never complete. To me, this feels more like beta software than a finished application.
Would the premium version of Grammarly have performed better on the so-called critical issues? I have no idea, but I rather doubt it. Automated checking of English grammar is incredibly difficult. In my opinion, it’s going to take a large company employing advanced AI to really crack the problem.
I did look for other reviews of Grammarly and found them mixed. Disturbingly, many of the positive ones end with buy links for Grammarly, suggesting that they may be biased or even paid for. The best reviews were those that looked at several different grammar-checkers and compared their performance to a human’s.
In summary, the free version of Grammarly can be a useful aid for finding some types of simple grammar issues. It caught typos that have been in my book for ages without anyone noticing. On the other hand, blindly following its suggestions would have wrecked my book, filling it with bizarre and ungrammatical sentences. So don’t even think of using Grammarly unless you already have a good knowledge of proper English grammar.