Regex Tester & Validator

This regex matches lines that begin with an English letter (a-z or A-Z) followed by zero or more word characters (letters, digits, or underscores). With the 'm' flag, ^ and $ match the start and end of each line, so it validates that every line is a simple identifier with no spaces or punctuation. It is useful for checking variable names, extracting identifiers from lists, or filtering lines that meet basic naming conventions.