LanguageTool is a style and grammar checker that currently supports English, Polish, German, French, Dutch, and other languages to a different degree. It scans the words and their part-of-speech tags for occurrences of error patterns, which are defined in an XML file. More powerful error rules can be written in Java. LanguageTool should be used after the spelling of a text has been corrected.

Many error detection rules have been updated, especially for French, Catalan, German, Portuguese, Russian, Esperanto, and Breton. Several small bugs have been fixed.

LanguageTool – Freecode

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