Slows down Firefox massively.

Would give this addon 4 stars, but it is not letting me log in at the moment which is quite annoying considering I use the personal dictionary feature quite often for work. The addon still works though, which is why I'm giving it 2 stars.

Unfortunately it's not allowing me to remain logged in. Very disappointing since I depend on this app for work and school purposes.

Can't log in! I tried to remove and reinstall it, but that is in vain.

It makes my Gmail super slow and Firefox often shows a popup that it's slowing down my browser generally. Suggestions are also not super useful all the time when compared to the built-in spell-checker.

great app, but I have the same problem as others, that the firefox add-on recognizes that I have a premium account but does not load the correction mode. It would be great if this bug could be fixed soon

Was working well, but now makes the gmail page slw down, Firefox throws up a pop-up asking whether to stop or disable temporarily. Makes gmail unusable

Removes spaces when I'm writing which is very annoying, other than that it is very good at spell checking.

doesn't login and doesn't work as well
"Grammarly is active, but
key features are missing"

Many features only in Pro version.

I tried it and uninstalled. It did not catch an uncapitalized first word in a sentence.

For new users make sure you "auto saved" all your documents every minute as it freezes and crash your web pages very often. When crashed a yellow bar appeared that reads "a script "Grammarly for Firefox" is slowing down your browser, temporary disable or stop it." If you are lucky only one tab crash, if not all and never respond again. Got to turn off power to restart your computer (very annoying).

Grammarly was completing my sentences with words that were not mine. I could not get rid of it. To my mind it is a defect in the program. There is no phone number or address to ask for help.

It offers very good functionality, however almost no configuration options. The plugin runs by default on all pages resulting in huge performance impact, severely increased memory use for Firefox and indeed privacy concerns.
Have you just started to type something sensitive on a page without remembering to disable Grammarly first? Bad luck, your data is already on their servers.
Setting the plugin to be disabled by default and only enabled on demand would be absolutely necessary. The way it is now, is shady and too pushy.
I can see how they want it to run everywhere, but still, this is a big no-no, to by default automatically send all my typing to a remote server.
Also the resource usage is really bad. If you use few tabs and restart browser every offten, probably it's fine, but I usually have several tens of tabs in variety of windows and Firefox running in one go for a week. Now, if you are such a user, disable this, and you'll be amazed how much better the overall responsiveness of Firefox will become.
Long story short: it offers nice feature, but the cost cannot be justified.
I'd just go to https://app.grammarly.com/ if I need writing assistance, and keep away from this plugin for good.

some time grammerly just sits there... dose nothing... just like right now as i am filling out this review...

Grammarly does not allow me to make any notations in Google Contats.