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Regex Tester
Test regular expressions with live highlighted matches, capture group details and quick pattern library. 100% private.
✅ Free ⚡ Live Testing 📐 Match Details 🔒 Private
⭐⭐⭐⭐⭐4.9 / 5(9,712 ratings)
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Live Testing
Tests your regex against the input string as you type, with colour-highlighted matches.
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Match Details
Shows every match with index, length and capture groups in a structured table.
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Quick Patterns
One-click common patterns: email, URL, phone, date, IP address and more.
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100% Private
All regex processing uses the browser's native JavaScript RegExp engine. Nothing is sent anywhere.
⭐ User Reviews
4.9
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Based on 9,712 verified reviews · 99% recommend
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The highlighted matches with colour coding by group make complex multi-group regexes easy to debug. I use it every day for log parsing patterns. The quick patterns are perfectly chosen.
Regex Tester⭐⭐⭐⭐⭐
Match details showing index and capture groups saved me 30 minutes of manual debugging on an email validation regex. The live testing updates as I type — exactly how a regex tool should work.
Regex Tester⭐⭐⭐⭐⭐
The flag checkboxes (g, i, m, s) are clearer than typing flags manually. I can toggle multiline and dotAll without remembering the exact letters. The quick pattern library covers 90% of my use cases.
Regex Tester⭐⭐⭐⭐⭐
Best free regex tester I've found. No sign-up, no ads, full match details including capture groups. I paste server log lines and instantly see which pattern matches. Essential for my data pipeline work.
Regex Tester📖 How to Use
1
Enter Pattern
Type your regex in the pattern field. Use the flag checkboxes to enable global, case-insensitive, multiline or dotAll modes.
2
Add Test String
Paste the text you want to test against in the Test String area.
3
Review Matches
Matches are highlighted in the output. Check the Match Details section for indices and capture groups.
4
Use Quick Patterns
Click any quick pattern button to load a pre-built regex for common use cases.
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❓ FAQ
What is a regular expression (regex)?+
A regular expression is a sequence of characters defining a search pattern. They are used for string matching, validation, extraction and replacement in programming, text editors, search engines and command-line tools.
What do the flags g, i, m, s mean?+
g (global) finds all matches instead of stopping at the first. i (case-insensitive) ignores case. m (multiline) makes ^ and $ match line starts/ends instead of string start/end. s (dotAll) makes . match newlines.
What are capture groups?+
Groups defined by parentheses () capture the matched text as a sub-match. They are referenced by number ($1, $2) or name (?…) in replacement strings, and returned in match arrays. Non-capturing groups use (?:…).
What is the difference between .test() and .match()?+
.test(regex) returns true/false. "string".match(regex) returns an array of matches (or null). With the g flag, match() returns all matches as strings. Without g, it returns the first match with groups.
Why does my regex work in one language but not another?+
Regex flavours differ between JavaScript, Python (re), PHP (PCRE), Java and others. JavaScript does not support lookbehind in older browsers, named groups syntax differs, and Unicode handling varies. This tester uses JavaScript's native RegExp.