Regex Tester
Test JavaScript regular expressions live in your browser. Enter a pattern and test string to instantly see match highlighting, match count, and capture group values.
Regular Expression Parameters
Regex Quick Cheat-Sheet Reference▼
- . - Any character except newline
- \d - Any digit (0-9)
- \w - Word character (a-z, A-Z, 0-9, _)
- \s - Whitespace character
- [abc] - Any character in brackets
- [^abc] - Any character NOT in brackets
- * - 0 or more times
- + - 1 or more times
- ? - 0 or 1 time (optional)
- {n} - Exactly n times
- {n,} - n or more times
- {n,m} - Between n and m times
- ^ - Start of string / line
- $ - End of string / line
- \b - Word boundary
- (abc) - Capture group
- (?:abc) - Non-capturing group
- (?<name>abc) - Named capture group
Embed this Tool on Your Website
Copy this code snippet to add the Regex Tester to your blog or website for free. It adjusts dynamically to mobile and desktop screens.
How to Use Regex Tester
Regex Tester Formula / How It Works
Pattern matching runs using JavaScript's native RegExp object. To prevent browser freezes from complex patterns, matching is executed with a 2-second timeout. If a pattern exceeds this limit, a warning is displayed.
For example, the pattern (\d+) with flag g applied to the string 'Order 1234, ref 5678' will find 2 matches: '1234' and '5678', displayed in the capture group table.
Frequently Asked Questions
This tester uses JavaScript regex syntax, which follows the ECMAScript standard. It supports common features including character classes, quantifiers, groups, lookaheads, and flags (g, i, m, s, u, y). It does not support PCRE-specific syntax like (?P<name>) or atomic groups.
Enter your regular expression in the pattern field and your test string in the input field. The tester instantly highlights all matches in the input string and shows capture groups, match positions, and match count in real time as you type.
Use it as a reference, but verify: JavaScript regex is mostly compatible with Python's re module and PHP's preg functions for common patterns. Java and .NET have different syntax for some features (e.g., lookbehind length limits). Always test in your target language for production use.
Supported flags: g (global — find all matches), i (case-insensitive), m (multiline — ^ and $ match line boundaries), s (dotAll — dot matches newlines), u (Unicode mode), y (sticky — match at exact position). Select flags using the checkboxes or enter them after the closing slash.
No. All regex matching runs in your browser using the JavaScript RegExp engine. Your patterns and test strings are never transmitted to any server or stored anywhere.
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