Firefox spell-checker and editing custom dictionary – persdict.dat

Firefox has a spell-checker inbuilt.You can enable spell-check in firefox, in your own language by adding the appropriate firefox dictionary add-on for your language.Firefox enables spell-checker only for HTML textarea elements, by default.However you can enable this spell-checker feature in firefox to any HTML textbox.The firefox spell-checker may be used, when you fill forms in websites or enter comments in blogs etc.To generalize it, the firefox spell-checker will work whenever you enter any text into HTML pages that have textarea or text elements.Enable firefox built-in spell-checker.

Firefox spell-checker - How to enable and edit

  • Double-click the layout.spellcheckDefault entry and change the integer value from 1 to 2 and click OK.

Firefox spell-checker - How to enable and edit

  • Open a new browser window or tab (or refresh an existing one) and test it out.

Firefox spell-checker - How to enable and edit

Disabling firefox spell-checking:

Mozilla allows you to turn off the spell check, which is a handy feature for us brainiacs. Just go to the Tools –> Options –> Advanced –> General and deselect the box that says “Check my spelling as I type“. The spell check will no longer function!

If you want to add bulk of custom words you can goto dictionaries folder which resides in Firefox installation folder and open the dictionary file of your language in wordpad and append the set of words to the bottom of the file.

Alternatively you can add the custom words to the custom dictionary file.The name of the custom dictionary is “persdict.dat” (short for “personal dictionary”), and is located in the following location (depending on operating system):

Windows Vista


Windows XP

C:\Documents and Settings\[username]\ApplicationData\Mozilla\Firefox\Profiles\[unique-alphanumeric-string].default\persdict.dat

Mac OS X

~/Library/Application Support/Firefox/Profiles/[unique-alphanumeric-string].default/persdict.dat



Of course, the [username] (for Windows) and [unique-alphanumeric-string] will vary depending on your unique configuration. Once you have located the target file, “persdict.dat“, open it with a text editor and edit according to your needs. The file itself is simply a list of words that you have chosen to add to the dictionary by right-clicking in Firefox and selecting “Add to dictionary“.

Note that “persdict.dat” will not be found in the above mentioned locations, unless you added custom words to the the dictionary. You can add a custom word marked as a typo to the dictionary by simply right-clicking and choosing – you guessed it – “Add to Dictionary” from the context menu.

0 comments on “Firefox spell-checker and editing custom dictionary – persdict.dat

  1. […] has spell-check dictionaries in a number of languages that can be be used to spell-check the content that you type in any textarea and textbox html elements on any webpage.To change the spell-check language, right click on any textarea or textbox html element and choose […]

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