LanguageTool

LanguageTool is an open-source browser extension that provides proofreading and grammar checking for a wide variety of languages. It identifies spelling, punctuation, and grammatical errors that standard spell checkers often miss. The software is available as a browser extension, a desktop application, and a server installation, allowing users to integrate linguistic checks into their existing writing workflows across different platforms.

Users can deploy the tool via a scripted installation process, build it from source using Apache Maven, or run it through community-contributed Docker files for easier containerization. It supports a flexible range of interfaces, including a graphical user interface for manual editing, a command line version for automated text processing, and a server version for centralized deployment. This versatility makes it suitable for both individual writers and organizations requiring a self-hosted proofreading solution.

Key features

• Support for over 30 languages including English, Spanish, French, and German
• Detection of complex grammatical errors beyond simple spell checking
• Availability as a standalone GUI application
• Command line interface for scripted text analysis
• Server mode for hosting the proofreading engine
• Integration options for LibreOffice and OpenOffice
• Ability to contribute custom error detection rules
• Support for shallow cloning to reduce build disk requirements

The core of the software is written in Java and requires Java 17 and Apache Maven for building from source. The architecture allows for the creation of specific packages, such as the Wikipedia package or the office-extension package, to tailor the tool to specific environments. It is designed for writers, editors, and developers who need multilingual support and the ability to host their own proofreading infrastructure without relying on proprietary cloud services. The project is distributed under the LGPL license, which ensures the core engine remains freely available for modification and redistribution.

LanguageTool serves as a privacy-focused and multilingual tool for users who require advanced linguistic analysis and the flexibility of self-hosting across different operating systems.