tools.regex-tester.title

A regular expression (sometimes called a rational expression) is a sequence of characters that specifies a search pattern in text. Usually, such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation. It is a technique developed in theoretical computer science and formal language theory.

Writing and debugging complex regular expressions can be challenging. An interactive, web-based Regex Tester allows developers and data editors to write regex rules and visually check how they capture and match words, characters, numbers, and symbols in real-time, preventing errors in production code.

1. Type your search pattern into the Regular Expression input box (omit the beginning and ending slashes as they are added automatically).
2. Select or deselect JavaScript regex flags underneath to control whether search should be global, case-insensitive, multi-line, etc.
3. Paste your raw text into the Test String block.
4. Inspect the matched highlights in the live preview panel on the right. Highlights will show exactly what characters match your regex.
5. Review the detailed Match Analysis table to view capture indexes and specific sub-groups.