Why isn't my pattern matching more than once?

Check whether the g (global) flag is on — without it, JavaScript's regex engine stops after the first match, even if more instances exist in the text.

What does the s (dotAll) flag do?

Normally, . (dot) matches any character except a newline. The s flag makes . also match newlines, which is useful when your pattern needs to span multiple lines.

Is my test text or pattern sent anywhere?

No — matching runs entirely in your browser using JavaScript's built-in regex engine; nothing is uploaded or transmitted.

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Regex Tester

Test a regular expression against text, with matches highlighted.

🔒 Runs entirely in your browser — nothing here is ever uploaded

About the Regex Tester

Tests a regular expression against sample text, highlighting every match directly in the text, using your browser's native, standards-compliant regex engine.

How to use it

Enter a Pattern (without the surrounding slashes).
Toggle the Flags you need — g for all matches, i for case-insensitive, m for multiline anchors, s for dotAll.
Enter or paste your Test text.
Read the match count and see every match highlighted in the text below.

Formula

Uses JavaScript's built-in RegExp engine (ECMA-262) directly — the same regex dialect and matching behavior your pattern would have in actual browser or Node.js code, not a separate simplified implementation.

Worked example

The pattern \b[\w.+-]+@[\w-]+\.[a-zA-Z]{2,}\b with the g and i flags finds every email-like substring in a block of text, highlighting each one in place.

Recommendations

• Without the g (global) flag, only the first match is found — turn it on whenever you expect (or want to check for) more than one match.
• The m (multiline) flag changes what ^ and $ mean — they match the start/end of each line instead of the start/end of the whole string, which matters for multi-line test text.
• An invalid pattern (unbalanced parentheses, a bad escape sequence) shows a real JavaScript regex error message — the exact error your own code would throw if you used that pattern directly.

Frequently asked questions

Yes — it runs JavaScript's native RegExp directly in your browser, so a pattern that works here will behave identically in actual JavaScript or Node.js code. Other languages (Python, PCRE, etc.) have their own regex dialects with some differences.