Regex Tester
Test and debug regular expressions.
How to use Regex Tester
Type your pattern and pick the flags you need, such as global or case-insensitive.
Paste the test text — matches are highlighted as you type.
Inspect the capture groups, or add a replacement string to preview the result.
Frequently Asked Questions
Which regex flavour is this?
JavaScript regular expressions, the same engine Node.js and every browser use. Most patterns from other languages work, though lookbehind support varies by browser.
Are capture groups shown?
Yes. Every match lists its numbered groups and any named groups, along with the index where the match starts in your text.
Can a regex hang the page?
A catastrophically backtracking pattern can be slow on long input. Matching is capped so the tab stays responsive, and you are warned when the limit is reached.
Related tools
Looking for something else? Browse all developer tools.