Has anybody signed up to use the online version?
Grammarly
Grammarly’s free writing app will make sure your messages, documents, and social media posts are clear, mistake-free, and impactful.www.grammarly.com
How does it compare to the software?
I use the free downloaded version for windows (which I believe actually works online), since I use MS-Word-97 (which is a little, hehe, out of date). Up until perhaps a month ago, it was rather comprehensive and specific. After a software update, it is now more vague, prompting you to buy the upgraded version via 'x-y-z specific issues' still exist (although, in most cases, that forces you to try various grammatical fixes and see if it satisfies/removes the prompt. That results in learning IMO).
I don't care if you're a literary genius or a writin' ignOramoose like me. It's easy enough to try then keep or pitch.
That said, many folks I speak with on a much-less professional writing forum I visit, were impressed enough that they bought it and are all extremely satisfied with the purchase. On the other hand, nothing can account for style or intentional misuses of grammar. So there will always be a point where you need to follow it mindlessly, and your paragraph will read exactly like mine, or, use it to polish 'your style' to the degree 'you' want.
K2