LanguageTool is a style and grammar checker that detects writing errors across more than twenty-five languages.
The tool addresses the limitation of spell checkers by identifying grammatical mistakes, style issues, and other errors that simple dictionary-based checking cannot catch. It works by applying language-specific rules to analyze text and flag problems ranging from basic grammar to nuanced style concerns. The project supports deployment as a standalone application, an HTTP server with a public API, or as an embedded Java library.
Developers should choose this tool if they need multilingual proofreading capabilities beyond spell-checking. It suits projects requiring either a self-hosted solution or integration into existing applications through its Java API or HTTP interface. The tool is particularly valuable for applications handling content in multiple languages, as it provides consistent error detection across a wide language set. Community-contributed Docker images are available for containerized deployment, though these are maintained separately from the core project.
The project maintains active development with regular updates to error detection rules and language support. The codebase is substantial, requiring over five hundred megabytes to clone fully, though shallow clones are available for reduced bandwidth. Building from source requires Java and Maven, with specific guidance provided for Apple Silicon systems. The development team actively solicits contributions through documented processes for adding new error detection rules, and comprehensive developer documentation is maintained separately from the main repository.
