Firefox has a built-in spellchecker.

Type about:config<enter> in the address bar. If a warning screen comes up, press the Be Careful button. At the top of the screen is a search bar.

Type: layout.spellcheckDefault Its values are; 0 Spell Checker Off 1 Check Only Multi-Line Input Boxes. 2 Check Multi And Single Line Input Boxes.

Also, check the spellchecker.dictionary entry.

There are other spellcheckers available at the Mozilla Add-ons Web Page {web link} (There’s a lot of good stuff here) and search for what you want.

Thank you FredMcD,

I am aware of the Firefox spellcheker. What I would need is to automatically correct the mispelled words.

I know that many (local) editors do it. Since I am not a heavy programmer, I do not know whether it is possible that a Firefox addon could do the same; that the reason I asked.

Most spell checkers work like this; If a word is not in their database, it tries to think of what word you want and gives you some possible choices. The user must then make a choice.

It is a inline spell checker in Firefox and not a auto-corrector.

It has not really changed much since it was first introduced on Firefox 2.0 Release as users were using a extension called Spellbound (not maintained by author for years now) on Firefox in the years before Firefox 2.0.

Oh how I wish Robert Strong had convinced Mozilla to integrate this Spellbound extension of his in Firefox when he joined Mozilla back then.