Test and debug regular expressions in real time. See all matches highlighted in your test string. View capture groups, match indices, and flags. Includes a quick-reference cheat sheet.
A regex tester lets you write and test regular expressions against sample text with live matching and instant visual feedback. Regular expressions are powerful pattern-matching tools used in programming for text search, validation, and manipulation. Our browser-based regex tester uses JavaScript's native RegExp engine to highlight all matches in real time, display capture groups, and show match indices. It supports all standard flags including global, case-insensitive, and multiline. Since everything runs locally in your browser, your patterns and test data remain completely private.
This tool uses JavaScript's built-in RegExp engine. The syntax is ECMAScript-compatible, which covers most common regex patterns.
Flags modify how the pattern matches: 'g' (global) finds all matches, 'i' is case-insensitive, 'm' makes ^ and $ match line boundaries, 's' makes . match newlines, and 'u' enables full Unicode matching.
Parentheses () in a pattern create capture groups, which extract specific portions of the match. Named groups use (?<name>...) syntax. Each match's groups are shown in the results.
Yes. The regex engine runs entirely in your browser. Your patterns and test strings are never sent to any server.