Online Regex Debugger
Real-time match highlighting, capture group visualization, common pattern templates Real-timeNo Dependencies
🔍 Regular Expression
📝 Test Text
✅ Match Results
📋 Common Patterns
Regex Debugger Online
Regular expressions are powerful tools for text processing, but their complex syntax makes them hard to debug. This tool provides real-time match highlighting and capture group visualization to help you quickly validate and debug regex patterns. All matching runs locally in your browser—no data is uploaded to any server.
Common Regex Patterns
- Email validation: Match standard email formats
- Phone numbers: Match US and international phone formats
- URL extraction: Extract all URLs from text
- IP addresses: Match IPv4 address format
- Date format: Match YYYY-MM-DD format
- HTML tags: Match HTML opening and closing tags
Regex Debugging Tips
- Start with a simple pattern and add complexity incrementally
- Use capture groups () to extract specific parts
- Watch out for greedy vs non-greedy matching (*? vs *)
- Use \u for Unicode character matching
- Consider using the x flag for comments in complex patterns
What is a regular expression?
A regular expression (Regex) is a text syntax for describing string patterns. It is widely used for text search, replacement, validation, such as email validation, URL extraction, and data cleaning.
How to debug a regex?
Enter your regex pattern and test text. The tool highlights all matches in real-time, showing match positions and capture group contents. Adjust the regex incrementally and observe matching changes.
What regex flags are supported?
JavaScript regex flags are supported: g (global), i (case-insensitive), m (multiline), s (dotAll), u (Unicode).
Is my data uploaded to a server?
No. All regex matching and debugging runs locally in your browser. No data is uploaded to any server.