About This Tool
Test and debug regular expressions in real time with live match highlighting, group capture display, and pattern explanation. Supports JavaScript regex syntax with global, case-insensitive, and multiline flags.
How to Use
Type or paste your regular expression pattern in the Pattern field. Toggle flags (g, i, m) as needed.
Enter your test string in the text area below. Matches are highlighted instantly as you type.
Check the Explanation panel to see a human-readable breakdown of what each part of your regex does.
Use the Substitution section to test find-and-replace operations with your pattern.
Frequently Asked Questions
What regex flavor does this tool support?
This tool uses JavaScript's built-in RegExp engine, which supports features like lookahead, lookbehind, named groups, and Unicode property escapes.
What do the g, i, and m flags mean?
g (global) finds all matches instead of stopping at the first. i (case-insensitive) ignores letter case. m (multiline) makes ^ and $ match the start/end of each line.
Can I use this for regex in other languages?
JavaScript regex is similar to most languages, but some features differ. Python, Java, and PHP use PCRE which has additional features like possessive quantifiers.
How do capture groups work?
Parentheses () create capture groups that extract parts of a match. Named groups use (?<name>...) syntax. The Match Details panel shows all captured groups.