Installing Language Tool in TexStudio

This is a recent and more detailed solution for Windows users.

1. Make sure the last version of TeXstudio is downloaded from its website.
2. Download the English dictionary (*.oxt) from here to the directory C:\Program Files (x86)\TeXstudio\dictionaries.
3. Download languagetools (*.zip) from its website.
4. Navigate to LanguageTool directory, then open languagetool.jar. Go to Text Checking > Options, then check Run as server op port and type the port number 8081. Click OK and close.

1. Open TeXstudio and go to Options > Configure TeXstudio > Language Checking while making sure the Show Advanced Options is checked.
2. Click on Import Dictionary... and navigate to C:\Program Files (x86)\TeXstudio\dictionaries, then choose the dictionary *.oxt you downloaded.
3. Make sure the default languae is selected (e.g. en_US), and the thesaurus is selected from the same directory (e.g. th_en_US_v2.dat).

1. Check Start LanguageTool if not running.
2. Set the values Server URL, Java, LT Path and LT Arguments to http://localhost:8081/, java(as recommended here), <directory of LanguageTool*-*>\languagetool.jar and org.languagetool.server.HTTPServer --port 8081, respectively.

In order to make sure everything is fine, click on Help > Check LanguageTool in TeXstudio. The output should be something like this