About Regex Tester
Test and debug regular expressions with live matching. See matches highlighted in real-time as you type your pattern and test string.
Features
- Live regex matching as you type
- Visual highlighting of matches
- Detailed match information with indices
- Capture group extraction
- Support for all JavaScript regex flags
- Error detection and validation
- Copy regex pattern with flags
- Sample patterns for learning
Regex Flags
- g (Global): Find all matches, not just the first
- i (Case Insensitive): Match regardless of case
- m (Multiline): ^ and $ match start/end of lines
- s (Dot All): . matches newline characters
- u (Unicode): Treat pattern as Unicode
Common Regex Patterns
| Pattern | Description | Example |
|---|---|---|
| \d+ | One or more digits | 123, 456 |
| \w+ | One or more word characters | hello, test123 |
| \s+ | One or more whitespace | spaces, tabs |
| ^start | Match at start of string | start of line |
| end$ | Match at end of string | end of line |
| [a-z] | Any lowercase letter | a, b, z |
| (abc) | Capture group | abc |
Use Cases
- Email Validation: Test email address patterns
- Phone Numbers: Extract phone numbers from text
- URL Matching: Find URLs in content
- Data Extraction: Extract specific data patterns
- Text Processing: Find and replace patterns
- Form Validation: Test input validation patterns
- Log Parsing: Extract information from logs
Tips for Writing Regex
- Start simple and add complexity gradually
- Use capture groups () to extract specific parts
- Test with multiple examples to ensure accuracy
- Use \b for word boundaries to match whole words
- Escape special characters with backslash \
- Use ? for optional matches, + for one or more, * for zero or more
- Test edge cases and special characters
Privacy & Security
All regex testing happens locally in your browser. Your patterns and test strings are never sent to any server, ensuring complete privacy.