Regular expressions (regex) are powerful patterns used for matching text. Our Regex Tester helps you test, debug, and understand regular expressions by showing real-time matches, explanations, and capturing groups.

Key Features

✓Real-Time Testing: See matches highlighted as you type
✓All Flags Supported: Global, case-insensitive, multiline, dotall, unicode
✓Match Details: View position, length, and captured groups
✓Pattern Explanation: Understand what each part of your regex does
✓Example Patterns: Load common regex patterns for emails, URLs, phone numbers
✓JavaScript Syntax: Uses JavaScript regex engine for accurate results

Common Regex Patterns

Pattern	Description	Example
\\d+	One or more digits	123, 4567
\\w+	One or more word characters	hello, test_123
\\s+	One or more whitespace	spaces, tabs
^start	Match at start of string	start of line
end$	Match at end of string	line end
[abc]	Match any of a, b, or c	a, b, c
[^abc]	Match anything except a, b, c	d, e, f
a\|b	Match a OR b	a, b

Regex Quantifiers

Zero or more times

Example: a* matches "", "a", "aa"

One or more times

Example: a+ matches "a", "aa", but not ""

Zero or one time (optional)

Example: a? matches "" or "a"

{n}

Exactly n times

Example: a{3} matches "aaa"

{n,}

n or more times

Example: a{2,} matches "aa", "aaa"

{n,m}

Between n and m times

Example: a{2,4} matches "aa", "aaa", "aaaa"

Use Cases

Form Validation

Validate email addresses, phone numbers, zip codes, and other user input

Text Processing

Extract data, find and replace text, parse log files and documents

Data Extraction

Pull specific information from text: URLs, dates, prices, identifiers

Code Search

Find patterns in source code, identify function calls, variable names

Regex Flags Explained

g (global): Find all matches instead of stopping after the first match
i (case insensitive): Match both uppercase and lowercase letters
m (multiline): ^ and $ match start/end of each line, not just the string
s (dotall): Dot (.) matches newline characters too
u (unicode): Enable full unicode support for matching

Frequently Asked Questions

How do I escape special characters?

Use a backslash before special characters: . ^ $ * + ? ( ) [ ] { } | \ Example: To match a literal dot, use \\.

What are capturing groups?

Parentheses () create groups that capture matched text. Example: (\d{3})-(\d{3})-(\d{4})captures three separate groups from a phone number like 123-456-7890.

Why isn't my pattern matching?

Common issues: forgetting to escape special characters, incorrect quantifiers, wrong flags. Try testing with simpler patterns first and gradually add complexity.

Can I test regex for other languages?

This tool uses JavaScript regex syntax. Most regex features are similar across languages, but some advanced features may differ. Always test in your target language's environment.

How do I match Unicode characters?

Enable the 'u' (unicode) flag and use Unicode property escapes like \p{Letter}or specific ranges. The unicode flag is required for emoji and many international characters.

Regex Tester

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