Regex Tester & Validator

A simple email validation pattern that matches lines containing a basic email format: a local part of one or more lowercase letters or digits, followed by @, then a lowercase domain name, a literal dot, and a lowercase TLD. With multiline and global flags, it validates each line independently across the entire input. This pattern rejects uppercase letters, special characters like dots/underscores/plus signs in the local part, and multi-level domains such as user@mail.example.com, making it suitable for basic tutorials or strict low-level filtering.