Grammalecte [fr] v2.2
Grammalecte is a French grammar checker.
It also includes:
— a conjugation tool (which contains approximately 8000 verbs),
— a text formatter (to automatically correct most of typographical mistakes),
— a lexicographer.
Unlike other grammar checkers, Grammalecte is written in full JavaScript, doesn’t require a server and can work offline. No data is sent online.
Grammalecte also exists for Thunderbird, Chrome, LibreOffice and OpenOffice.
No support in the comments.