Is Regex Tester & Debugger free to use?

Yes, this tool is completely free with no limitations. No registration or payment required.

Absolutely. All processing happens in your browser. Your data never leaves your device and is not uploaded to any server.

Regex Tester

Test regular expressions in real-time with match highlighting and group extraction.

Regular Expression

/ /

Quick patterns:

Matches

Groups

Execution Time

0ms

Test String

Matches Highlighted

Match Details

No matches found

Replace

Replacement String (use $1, $2 for groups)

Result

Frequently Asked Questions

g (global) finds all matches, i (case insensitive) ignores case, m (multiline) treats each line as separate, s (dotall) makes . match newlines, u (unicode) enables full Unicode support.

Parentheses () create capturing groups that extract parts of a match. Use $1, $2, etc. in the replacement string to reference captured groups. Named groups (?<name>...) can be referenced with $<name>.

Lookahead (?=...) and (?!...) check what follows without including it. Lookbehind (?<=...) and (?<!...) check what precedes. They're useful for conditional matching without consuming characters.