Free Online Regex Tester
Test and debug regular expressions in real-time. See matches highlighted and cap...Test and debug regular expressions in real-time. See matches highlighted and capture groups extracted with built-in cheat sheet.
Regex Cheat Sheet
Characters
.- Any character\d- Digit [0-9]\w- Word [a-zA-Z0-9_]\s- Whitespace
Quantifiers
*- 0 or more+- 1 or more?- 0 or 1{n,m}- n to m times
Anchors
^- Start of string$- End of string\b- Word boundary\B- Non-boundary
Groups
(abc)- Capture group(?:abc)- Non-capturea|b- Or[abc]- Character class
Tester Features
Why Use Free Online Regex Tester?
Real-Time Matching
See matches highlighted instantly as you type. No need to click buttons or wait for results.
Capture Group Details
View each capture group separately with clear labeling. Perfect for complex patterns with multiple groups.
Replace Mode
Test find-and-replace operations with group references ($1, $2). Preview the result before using in your code.
Built-in Cheat Sheet
Quick reference for common regex syntax. Character classes, quantifiers, anchors, and groups at a glance.
Common Uses for Regex Tester
Email Validation
Test and refine email validation patterns for forms and input fields.
Code Refactoring
Build find-and-replace patterns for bulk code changes across files.
Log Parsing
Extract specific data from log files using capture groups.
Input Sanitization
Create patterns to validate and sanitize user input in applications.
How It Works
Enter Your Pattern
Type your regular expression in the pattern field. Use the common patterns buttons for quick templates like email or phone validation.
Configure Flags
Select flags to modify matching behavior. Use "Global" to find all matches, "Case Insensitive" for flexible matching, or "Multiline" for line-based patterns.
Test and Refine
Enter test text to see matches highlighted in real-time. View capture groups in the details panel. Enable replace mode to test substitutions.
Regex Tips
Start Simple
Build your regex incrementally. Start with a simple pattern that matches broadly, then add specificity. Test each change in real-time.
Use Common Patterns
Click the pre-built pattern buttons for email, URL, or phone validation as starting points, then customize for your specific needs.
Escape Special Characters
Characters like . * + ? { } [ ] ( ) | \ ^ $ have special meaning in regex. Use a backslash (\) to match them literally.