Regex Editor & Tester

Matches any single character that is NOT in an allowed whitelist: whitespace, word/digit characters, Russian typographic symbols (guillemets «», curly quotes, № numero sign, — em dash), and common punctuation (@ / \ - ( ) ! ? . , : ; % = + * [ ] ~). Used on the Russian government services portal (Госуслуги) to detect invalid characters in a cover letter field. With global and multiline flags, it finds every disallowed character across all lines of user input for validation or sanitization.