Regex Tester & Validator

This Golang regular expression validates version 4 UUIDs (Universally Unique Identifiers) as generated by the Google UUID package. It strictly checks the standard 8-4-4-4-12 hexadecimal format, enforcing the version number '4' in the third block and restricting the variant block to valid characters. It is commonly used for data validation, API payload verification, and database entity identification. Note that the `[8|9|aA|bB]` character class unintentionally matches the literal pipe character, though its intended use remains strict UUID validation.