What is Regex Tester?
Regex Tester is a free online tool for testing and debugging regular expressions. Enter your pattern and test string, and see matches highlighted in real-time. The tool provides match groups, flags support, and helpful error messages for invalid patterns.
Common Use Cases
Pattern Development
Build and test complex regex patterns interactively.
Data Validation
Create patterns for validating emails, phones, and other formats.
Text Extraction
Develop patterns for parsing and extracting data from text.
Search and Replace
Test regex patterns before using in code or text editors.
How to Use This Tool
- Enter your regular expression pattern
- Toggle flags (global, case-insensitive, multiline)
- Enter test text to match against
- View highlighted matches and capture groups
Frequently Asked Questions
What regex flavor is used?
This tool uses JavaScript regex, which follows ECMAScript standards. Most patterns are compatible with other languages.
How do I match across lines?
Enable the multiline (m) flag. Also, use [\s\S] instead of . to match newlines.
What is a capture group?
Parentheses () create capture groups that extract specific parts of a match. Access them as $1, $2, etc.