Regex Tester
Test and debug regular expressions with live matching and highlighting. Uses JavaScript regex engine.
🔍 Regular Expression
📝 Test String
✨ Match Results
0 matches📋 Match Details
📚 Common Patterns
📖 Quick Reference
.
Any character
\d
Digit [0-9]
\w
Word char
\s
Whitespace
^
Start of line
$
End of line
*
0 or more
+
1 or more
?
0 or 1
{n}
Exactly n
[abc]
Character set
(group)
Capture group
Frequently Asked Questions
A regular expression is a sequence of characters that defines a search pattern. It's used for pattern matching in strings, like finding email addresses, phone numbers, or validating input formats.
We support all common flags: global (g), case-insensitive (i), multiline (m), dotAll (s), and unicode (u). Toggle them on or off to customize your pattern matching.
Yes, our tester displays all captured groups for each match, including named groups. This helps you debug complex patterns with multiple capture groups.
Our tester uses JavaScript regex syntax, which is compatible with most languages. Note that some advanced features may vary between regex engines (PCRE, JavaScript, Python).
Yes, you can enter a replacement pattern to see how your regex would transform the test string, including backreferences to captured groups.
Free Online Regex Tester for JavaScript
Regular expressions (regex) are powerful patterns for matching, searching, and manipulating text. Our regex tester helps you develop and debug patterns with instant visual feedback, showing exactly what your pattern matches in the test string.
Real-Time Match Highlighting
As you type your pattern and test string, matches are highlighted instantly. This immediate feedback helps you understand exactly what your regex captures, making it easier to refine patterns and catch errors early.
Capture Groups and Match Details
When your pattern includes capture groups, our tool shows each group's contents separately. This is essential for patterns that extract specific parts of matched text, like parsing structured data or URLs.
JavaScript Regex Engine
This tool uses JavaScript's native RegExp engine, ensuring your patterns work identically when used in web applications, Node.js, or any JavaScript environment. All standard JavaScript regex features and flags are supported.