Regex Tester
Test and debug regular expressions in real-time. Visualize matches, get explanations, and learn regex patterns.
Regular Expression Pattern
Test String
Total Matches
0
Pattern
/pattern/
Flags
g
Test Time
0ms
Regex Pattern Explanation
Replace Matches
Replaced Result:
Regex Cheatsheet
Character Classes
.
Any character except newline
\d
Digit (0-9)
\w
Word character (a-z, A-Z, 0-9, _)
\s
Whitespace (space, tab, newline)
[abc]
Any of a, b, or c
Quantifiers
*
0 or more
+
1 or more
?
0 or 1
{3}
Exactly 3
{3,5}
Between 3 and 5
Anchors
^
Start of string
$
End of string
\b
Word boundary
\B
Not word boundary
Groups & Lookarounds
(abc)
Capture group
(?:abc)
Non-capturing group
(?=abc)
Positive lookahead
(?!abc)
Negative lookahead
Email Validation
\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b
Matches standard email addresses
Phone Number
(\+\d{1,3}[-.]?)?\(?\d{3}\)?[-.]?\d{3}[-.]?\d{4}
Matches various phone number formats
URL Pattern
https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)
Matches HTTP/HTTPS URLs
Date (YYYY-MM-DD)
\d{4}-\d{2}-\d{2}
Matches dates in YYYY-MM-DD format
IP Address
\b(?:\d{1,3}\.){3}\d{1,3}\b
Matches IPv4 addresses
Strong Password
^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$
At least 8 chars with upper, lower, number & special
About Regular Expressions
Regular expressions (regex) are patterns used to match character combinations in strings. They are incredibly powerful for text processing, validation, and extraction.
Common Use Cases:
- Form Validation: Validate emails, phone numbers, passwords
- Data Extraction: Extract specific information from text
- Search & Replace: Find and replace patterns in text
- Text Parsing: Parse log files, configuration files
- Input Sanitization: Remove unwanted characters from input
- URL Routing: Match URL patterns in web frameworks
Key Features of This Tester:
- Real-time Testing: See matches as you type
- Visual Highlighting: Matches are highlighted in the test string
- Detailed Explanation: Understand how your regex works
- Capture Groups: View and test capture groups
- Replace Functionality: Test regex replace operations
- Cheatsheet: Quick reference for regex syntax
- Examples: Common regex patterns to learn from
- History: Save and reuse your regex patterns
Performance Tips:
- Be Specific: Use precise character classes instead of .*
- Avoid Catastrophic Backtracking: Use possessive quantifiers when possible
- Use Anchors: Use ^ and $ when matching entire strings
- Optimize Groups: Use non-capturing groups (?:) when you don't need capture
- Test Edge Cases: Always test with both valid and invalid inputs
Browser Compatibility:
This tool uses JavaScript's built-in RegExp engine, which is supported in all modern browsers. Some advanced features (like lookbehind) may have limited browser support.
Note: All processing happens in your browser. Your data never leaves your computer, ensuring complete privacy.