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Developer utility
Regex Tester
Test JavaScript regular expressions with live matches, capture groups, named groups, flags, highlighted text, and replacement output directly in your browser.
Waiting for input.
Matches0
Groups0
Flags-
Runtime0 ms
Match list
Matches and positions
| # | Match | Index | Length | Groups |
|---|
Capture groups
Numbered and named groups
| Match | Group | Value |
|---|
Preview
Highlighted test text
Replace
Test replacement output
Examples
Common regex tests
Regex quick reference
| Token | Meaning | Example |
|---|---|---|
. | Any character except newline unless dotAll is enabled. | a.c |
\d | Digit character. | \d{4} |
\w | Word character: letters, digits, underscore. | \w+ |
+ | One or more of the previous token. | \w+ |
* | Zero or more of the previous token. | .* |
? | Optional token or lazy quantifier marker. | https? |
() | Capture group. | (\d{4})-(\d{2}) |
(?<name>...) | Named capture group. | (?<year>\d{4}) |
^ / $ | Start and end anchors. | ^Title |
\b | Word boundary. | \bcat\b |
Notes for JavaScript regular expressions
- The tester uses the browser JavaScript RegExp engine, so syntax follows JavaScript support in the current browser.
- The global flag is useful for finding every match; the tester adds it internally for scanning when needed.
- Use named groups such as
(?<year>\d{4})when replacement output needs readable placeholders. - Very broad patterns such as
.*can match empty text. The tester guards zero-length matches to keep the page responsive.
Regex tester FAQ
Is this a JavaScript regex tester?
Yes. It uses the native JavaScript RegExp implementation in your browser.
Can I use replacement variables?
Yes. JavaScript replacement syntax such as $1, $2, and $<name> works in the replacement field.
Why do some PCRE patterns fail?
JavaScript regex does not support every PCRE feature. Browser support also depends on the user's current JavaScript engine.