Maven tips

LanguageTool uses Maven 3.x since release 2.1 of LanguageTool. Here you will find some tips for building LanguageTool with Maven.

The Basics

You can build everything with this command, called in the top-level directory of where you checked out LanguageTool:

mvn clean package

The results (so-called artifacts in Maven lingo) can be found here:

  • languagetool-standalone/target/ this is the standalone version with the GUI and command line tool
  • languagetool-office-extension/target/ despite being called *.zip, this is the *.oxt for LibreOffice/OpenOffice. Rename it to *.oxt and install it with the LO/OO extension manager.

If you're not familiar with Maven, we suggest you always call Maven from the top-level directory. You can call it from most of the sub-directories, but then only that module will be built and other parts might be outdated.


Maven comes with some overhead. If it's too slow for you, these tips might help:

  • If you want to run only the tests for language "xy" and still be sure that everything this language module depends on is re-built, use (e.g. ./ xy test) or call this command: mvn --projects languagetool-language-modules/xy --also-make clean test
  • Don't use Maven that much: seriously, Maven is a build tool and most development can be done without building the software.
    • As a rule developer, use or testrules.bat to run our automatic tests of the grammar.xml rule files. Call ./ en to run only the English tests etc., which is much faster than running all tests.
    • As a Java developer, call mvn clean test to run all tests (this also isn't fast, but that's not so much a Maven problem). Do all other work directly in your IDE, so you won't need Maven for that. This assumes that you have properly imported all LanguageTool projects once. All modern IDEs should be capable to do that or they should have some plugin for it.
  • Build but skip all unit tests: mvn clean package -DskipTests
  • If you build often you can comment out dependencies to languages not interesting to you in the top-level pom.xml and in languagetool-language-modules/all/pom.xml
  • Use mvn -T 1C test to run the tests with 1 thread per CPU core, or mvn -T 2 to use 2 threads.


If something doesn't work, make sure you did mvn clean in the top-level directory of LT. This way remainders of old Maven runs will be deleted. If there are problems with dependencies, try this command:

mvn dependency:tree

It will show you the dependencies of the current project (i.e. the project whose directory you are currently in).

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