Regex Tester
Test and debug your regular expressions in real time. See matches highlighted instantly, inspect capture groups, and preview replacements — all in your browser.
Quick Reference
.Any character\dDigit [0-9]\wWord char [a-zA-Z0-9_]\sWhitespace^Start of string$End of string*0 or more+1 or more?0 or 1{n,m}n to m times[abc]Character class(group)Capture group(?:x)Non-capturing group(?<name>x)Named groupx|yAlternation\bWord boundaryFrequently Asked Questions
What is a regular expression?
A regular expression (regex) is a sequence of characters that defines a search pattern. It is used for pattern matching within strings — finding, validating, extracting, and replacing text. Regex is supported in virtually all programming languages including JavaScript, Python, Java, and Go.
What do the flags mean?
g (global) finds all matches instead of stopping at the first. i makes the match case-insensitive. m (multiline) lets ^ and $ match line boundaries instead of the full string. s (dotall) lets the dot (.) match newlines. u enables full Unicode matching.
How do capture groups work?
Parentheses (...) create capture groups that extract parts of a match. You can reference them in replacements as $1, $2, etc. Named groups use the syntax (?<name>...) and can be referenced as $<name>. Non-capturing groups (?:...) group without capturing.
Is my data processed on a server?
No. All regex testing runs entirely in your browser using JavaScript's built-in RegExp engine. Your data never leaves your device.