Regex Tester & Debugger
Test JavaScript regular expressions live with match groups and instant visual highlighting.
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Test String
Live Highlighted Matches
Match Details & Capture Groups
Match details will appear here...
Regex Cheat Sheet & Tips
Character Classes
\d Digit [0-9]\w Word char [a-zA-Z0-9_]\s Whitespace. Any character
Quantifiers
* 0 or more+ 1 or more? 0 or 1{3,5} 3 to 5 times
Anchors & Groups
^ Start of line$ End of line(...) Capturing group(?:...) Non-capturing group
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Working on scheduled expressions or pattern matching? Check out the Cron Expression Parser, or sanitize query parameters with the URL Encoder.
❓ Frequently Asked Questions
Q. Which regex flavor is evaluated?
The tester runs the native ECMAScript regular expression engine, supporting flags (g, i, m, s, u, y), lookahead/lookbehind assertions, and named capture groups.
Q. Does it highlight capture groups and indices?
Yes. Match results, numbered capture groups, and named group variables are dynamically color-coded with character start and end indices.
Q. Will catastrophic backtracking freeze my browser?
Execution is guarded by local execution timeouts to protect your browser tab from freezing when evaluating complex nested quantifiers.