Regex Tester
Test regular expressions in real-time. Matches are highlighted instantly as you type. Supports global, case-insensitive, multiline, and dotAll flags.
Real-Time Matching
Match Highlighting
Replacement Testing
Examples:
//g
Matches will be highlighted here...
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Mastering Regular Expressions
Regular expressions (regex) are powerful pattern-matching tools used in virtually every programming language. Mastering them unlocks efficient string searching, validation, and transformation. Our online regex tester makes learning and debugging regex fast and visual.
Essential Regex Flag Guide
| Flag | Name | Effect |
|---|---|---|
| g | Global | Find all matches, not just the first |
| i | Case-Insensitive | Match uppercase and lowercase equally |
| m | Multiline | ^ and $ match start/end of each line |
| s | DotAll | . matches newline characters too |
Common Regex Use Cases
- Email Validation:
[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,} - URL Extraction:
https?://[^\s]+ - Phone Numbers:
\(?\d{3}[-.\s]?\d{3}[-.\s]?\d{4} - Find Numbers:
\d+