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LanguageTool is an open-source grammar checker that has a library of over 3,000 English rules.

Since Vale Server focuses (primarily) on writing style rather than grammatical correctness, integrating with LanguageTool provides a nice balance of functionality: Vale Server will enforce your style guide while LanguageTool checks your grammar.

Additionally, by using this add-on, you also get to take advantage of Vale Server's understanding of markup—which LanguageTool lacks altogether on its own.


The first step is to install LanguageTool's standalone desktop application.

After downloading and unzipping the LanguageTool-x.x folder, select your installation location from Vale Server's extension preferences (Preferences -> Extensions):

A screenshot of Vale Server's 'Extensions' page.

LanguageTool requires Java 8 or later. If Java is already installed, it will show up under "Java" automatically. You can also manually enter your own path to a java installation.

Once you have the required fields configured, click "Apply & Restart". If the LanguageTool server started successfully, you'll see its URL displayed above the settings:

A screenshot of Vale Server's 'Extensions' page.

If you the LanguageTool server failed to start, see the Server Log option from the context menu for more information.



Currently, only rules listed in the MISC, GRAMMAR, CONFUSED_WORDS, and TYPOS categories are enabled.

Once LanguageTool is running in the background, you simply need to add LanguageTool to your BasedOnStyles list in one of your projects:

A screenshot Vale Server's project management dialog.

You'll now see results from LanguageTool in our client plugins.

Performance tuning#

By default, Vale Server will give LanguageTool 2 seconds of processing time before moving it to the background and showing its cached results on another invocation (typically a file-save event in an editor).

You can increase this value by providing another value for ProcessTimeout in your configuration file:

A screenshot Vale Server's project management dialog.