EDIT: thanks for the reply! So, although this add-on is not a spell checker, it may be connected locally to one, a HUGE one, for that matter (about 180 MiB currently, plus some gibibytes/gigabytes, according to the developer). It's in Java, what means it could be downloaded for off-line use on different platforms (yes, I know Java is not as portable as advertised, but that's not the point...) I'm granting the five stars based on the on-line results, because my conscience won't let me use a spell checker that is bigger than all my text editors plus browsers plus pretty much every piece of software that can handle texts on my computer. I think it could be an amazing tool for publishers (although it would probably choke parsing texts like those by Philip K. Dick...)

buen funcionamiento y muy intuitivo

alles gut ist supper

Good spell-checker. Unfortunately all features are not free, and it tries a bit too hard to make you enable it on all websites.

Accurate and Reliable.

Erstklassiges Tool , und ein super Support,

A extensão é excelente. Não é invasiva, porém é presente sempre que necessária, verificando a ortografia e a sintaxe.
Recomendo a sua instalação.

Super !

It simply does not work. It does not detect any spelling errors.
I entered this text:
Recibbee un cccordial sallludo de mi ppaarte
It did not recognise a single spelling error.

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