It's even worse than the built in spell checking of FF.

It isn't shown on here, but if you click the link in their "about" section, you can see that they now use AI to scan and check your text, which is probably why I've been getting so many errors in it lately, including ones for proper nouns that weren't there before.

In short, don't use it. It doesn't work like it used it, and as it is using AI, there is the potential for it to be using your own text to train models. Uninstall it if you have it already.

Causes a memory leak.

Lo uso mucho

This extension doesn't even work most of the time!

This is an evil extension!!! Why? We have been scratching our heads to find out why there is a consistent memory leak issue. It has wasted a lot of our precious time! Moreover, we even consider adding more memory but the memory price is very high now! We have never felt such pain in recent years! We are very angry that this poor plugin is so popular and has not fixed this issue in the shortest time.

Fabulous!

Muito util

Too bad it stopped working and you only have premium now.

A huge thank you to the person who wrote a review below. I've been using this extension for five years, and in the latest version, either there's an unintentional bug, or the developers intentionally introduced a leak that hadn't existed for 10 years.
This extension is currently causing a memory leak in the browser, even when I'm not opening anything and only on one page. It reaches 60 gigabytes for me, after which everything in the OS starts crashing with errors, from the browser to other programs.

I've been racking my brains for 2-3 weeks of torment, I couldn't figure out what was going on, because I've been using all the extensions for years and everything has been working without a hitch for a long time.
And it turns out that's what it is. The extension, which had been reliable for years, is now leaky and buggy, leaking 40-60 gigs of memory.
As soon as I removed this extension, everything has been fine for several weeks now.