Regex Tester & Validator

Matches any run of 4 or more identical consecutive letters (e.g., 'aaaa', 'zzzzz', or 'Oooo' with the case-insensitive flag). It captures one letter in a group, then uses a backreference (\1) followed by {3,} to require the exact same letter 3 or more additional times. Commonly used for spam detection, flagging elongated words like 'sooooo' or 'hellooo', or validating user input against excessive character repetition.