Regex Builder with Explanation

Who This Is For

Developers who need a reliable regex but find the syntax cryptic — or who want to understand what an existing regex actually does.

What Problem It Solves

Regex is notoriously difficult to write correctly, especially for edge cases like international characters, optional groups, or nested patterns. This prompt builds the correct expression for your use case, explains it character by character, and provides test cases to validate it.

Example Use Cases

• Validating an email address format in a form with specific domain rules
• Parsing structured log lines to extract timestamps and error codes
• Sanitizing user input by matching and removing specific character patterns

What to Expect

The final regex, a character-by-character explanation in plain English, working code showing how to use it in your language, and a test table showing which strings it matches and which it rejects.