Regular expression (regex) tester online
Test regular expressions live: match highlighting, capture groups, flags and replace. Includes ready-made patterns for email, URLs and more.
Matches
| # | Match | Index | Groups |
|---|
How it works
Type your regular expression and test text: matches are highlighted as you type, and below you see each one with its position and capture groups. You can toggle the g, i, m, s and u flags.
Fill in the replace field to see the result of applying the regex, using $1, $2 or $<name> to insert groups. Includes sample patterns for email, URL, phone numbers and dates. It uses the browser JavaScript engine.
Frequently asked questions
Do regexes work the same in every language?
The basics are shared, but there are differences (lookbehind, named groups, flags). This tool uses the JavaScript engine.
Why does my regex hang?
Some patterns with nested quantifiers, like (a+)+, cause "catastrophic backtracking". Simplify the pattern or make it more specific.
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