Regex Tester
Test and debug JavaScript regular expressions online. Live match highlighting, capture group inspection, flag support (gim), and instant syntax error feedback.
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How to Use Regex Tester
- 1Enter your regular expression pattern in the "Pattern" field (without slashes).
- 2Select flags: g (global), i (case-insensitive), m (multiline).
- 3Type or paste your test string in the text area below.
- 4Matches are highlighted in real time and capture groups are listed.
Frequently Asked Questions
What regex flavour does this use?
This tester uses JavaScript's built-in RegExp engine, which follows the ECMAScript specification. It supports most common features but not some advanced PCRE features like lookbehind (in older browsers) or named groups in all environments.
What does the "g" flag do?
The global ("g") flag makes the regex find all matches in the string. Without it, only the first match is returned.
How do I match a literal dot?
In regex, a dot (.) matches any character. To match a literal period, escape it with a backslash: \.
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