Regex Tester & Validator

This regex matches strings that start with a colon, capture everything after it into group 1, and then require the literal text 'Cool!' to appear immediately after that captured content. Due to greedy matching, it effectively matches any line beginning with ':' that ends with 'Cool!', with at least one character in between. It demonstrates PCRE conditional groups, where the condition (1) checks if capture group 1 participated, which always succeeds here. Useful for validating or parsing colon-prefixed labels that must carry a specific suffix, or for learning how conditional patterns work.