Regex Editor & Tester

Validates a username consisting of 5 to 12 alphanumeric characters (letters a-z and digits 0-9). With the case-insensitive flag, uppercase letters A-Z are also permitted. Anchors (^ and $) ensure the entire string matches, rejecting spaces, symbols, underscores, or strings that are too short or too long. Commonly used in JavaScript form validation for user registration and account creation.