Yes, 100% free. Test and debug regular expressions with no sign up or login required.

What regex flavors are supported?

Regex Hut uses JavaScript regex engine, which supports most common regex features including lookahead and lookbehind.

Can I see capture groups?

Yes. Regex Hut highlights all matches and displays capture groups with their values in real-time.

Is my test data sent to a server?

No. All regex testing happens locally in your browser. Your data stays on your device.

Can I save and share my regex patterns?

You can copy the regex pattern and test string. All processing is local for your privacy.

Regex Tester & Debugger

Test and debug regular expressions online for free with real-time match highlighting, replace preview, and a library of common regex patterns. Everything runs in your browser.

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Test Text

Enter a regex and test text to see matches

Enter a regex to see an explanation

How to Use

Enter your regular expression in the pattern field above.
Toggle flags (g, i, m, s, u) as needed.
Type or paste your test text — matches highlight in real time.
Switch to Replace mode to test substitutions.
Browse the Regex Library for common pattern templates.

FAQ

A regular expression is a sequence of characters that defines a search pattern. It is used for string matching, searching, and text manipulation. In JavaScript, regex is created with /pattern/flags syntax or the RegExp constructor.

A simple email regex is ^[^\s@]+@[^\s@]+\.[^\s@]+$. This matches strings with a local part, @ symbol, and domain. For production use, consider more comprehensive patterns or use a validation library.

g (global) finds all matches, not just the first. i (case insensitive) ignores letter case. m (multiline) makes ^ and $ match start/end of each line. s (dotAll) makes . match newlines. u (unicode) enables full Unicode matching.

Greedy quantifiers (*, +, {n,m}) match as much as possible. Lazy quantifiers (*?, +?, {n,m}?) match as little as possible. For example, given "<b>bold</b>", the pattern <.+> (greedy) matches the entire string, while <.+?> (lazy) matches only "<b>".

Capture groups are defined with parentheses (pattern). They capture the matched text so you can reference it in replacements using $1, $2, etc. Named groups use (?<name>pattern) syntax. Non-capturing groups (?:pattern) group without capturing.