LanguageTool is an Open Source proofreading tool. This website lists LanguageTool's error detection rules and supports you in writing new ones.
Browse Rules
LanguageTool uses rules to detect errors. Each rule represents a potential error in the text to check. Have a look at all rules of all languages here.
Text Analysis
Show how LanguageTool analyses text, to understand why rules match or not match
Rule Editor
Try our rule editor to create new error detection rules
LanguageTool 6.7-SNAPSHOT (2025-07-02 22:33:10 +0200)