Free OnlineDeveloper Tools
Regex Tester
Test and debug regular expressions in real time. Match, capture, and replace with live highlighting and explanations.
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//g
Flags:
Key Features — Regex Tester
Real-time match highlighting
Capture group identification
Support for global, multiline, and case-insensitive flags
Match information with index positions
Common regex pattern library
Why Use This Tool — Regex Tester
Free Online Regex testerRegular expression tester — for EveryoneFast & Easy Regex debuggerRegex validator — 100% FreeFree Online Test regex online
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Frequently Asked Questions — Regex Tester
What regex flavor does the tester use?
The tool uses JavaScript regular expressions, which follow the ECMAScript specification. This includes features like lookahead, lookbehind, named capture groups, Unicode property escapes, and the dotAll flag. Syntax specific to other flavors like PCRE may not be supported.
How do I use capture groups?
Wrap part of your pattern in parentheses to create a capture group. For example, (\d{3})-(\d{4}) captures the area code and number separately. Named groups use (?<name>...) syntax. The tool displays each group's match value and index.
Can I use the regex tester for find and replace?
Yes. Enter your regex pattern, test string, and a replacement string. The tool shows the result of the replacement in real time. You can use backreferences like $1 and $2 or named references like $<name> in the replacement string.