Regex Tester & Generator

A regular expression is a sequence of characters that forms a search pattern. It's used for string matching, search and replace operations, and data validation.

No. Our Regex Tester runs 100% locally in your browser. None of your text or patterns are sent to our servers.

This tool uses the JavaScript (ECMAScript) regex engine, which supports standard modern regex features including lookaheads, lookbehinds, and named capture groups.

'g' (global) finds all matches rather than stopping after the first. 'i' (ignoreCase) makes the match case-insensitive. 'm' (multiline) makes the ^ and $ anchors match the start and end of lines, not just the whole string.

Yes! By wrapping parts of your pattern in parentheses (like `(pattern)`), you create 'capture groups' which are extracted and displayed separately in our analysis panel.

This usually happens due to unescaped special characters (like `[`, `(`, `+`, `*`) or unbalanced parentheses. Check the error message displayed below the input box for hints.

To match an exact phrase, simply type the phrase. To ensure it matches a whole word and not a substring, use word boundaries like `\bphrase\b`.

We provide a built-in predefined pattern for email validation. Select 'Email Address' from the Quick Pattern Generator dropdown to see a standard email matching regex.

Currently, we focus on clear match analysis and group extraction. The matches are highlighted in the results panel to show exactly what was found and at what index.

Yes, the Regex Tester is fully responsive and works beautifully on mobile devices, tablets, and desktops alike.