Free Online Regex Tester
Test, parse, and debug your regular expressions with live syntax highlighting. Validate regex patterns for emails, URLs, numbers, and custom string filters in real-time.
About Regex Tester
Regular expressions (regex) are powerful patterns used for matching text. Our Regex Tester helps you test, debug, and understand regular expressions by showing real-time matches, explanations, and capturing groups.
Key Features
- ✓Real-Time Testing: See matches highlighted as you type
- ✓All Flags Supported: Global, case-insensitive, multiline, dotall, unicode
- ✓Match Details: View position, length, and captured groups
- ✓Pattern Explanation: Understand what each part of your regex does
- ✓Example Patterns: Load common regex patterns for emails, URLs, phone numbers
- ✓JavaScript Syntax: Uses JavaScript regex engine for accurate results
Common Regex Patterns
| Pattern | Description | Example |
|---|---|---|
| \\d+ | One or more digits | 123, 4567 |
| \\w+ | One or more word characters | hello, test_123 |
| \\s+ | One or more whitespace | spaces, tabs |
| ^start | Match at start of string | start of line |
| end$ | Match at end of string | line end |
| [abc] | Match any of a, b, or c | a, b, c |
| [^abc] | Match anything except a, b, c | d, e, f |
| a|b | Match a OR b | a, b |
Regex Quantifiers
Zero or more times
Example: a* matches "", "a", "aa"
One or more times
Example: a+ matches "a", "aa", but not ""
Zero or one time (optional)
Example: a? matches "" or "a"
Exactly n times
Example: a{3} matches "aaa"
n or more times
Example: a{2,} matches "aa", "aaa"
Between n and m times
Example: a{2,4} matches "aa", "aaa", "aaaa"
Use Cases
Form Validation
Validate email addresses, phone numbers, zip codes, and other user input
Text Processing
Extract data, find and replace text, parse log files and documents
Data Extraction
Pull specific information from text: URLs, dates, prices, identifiers
Code Search
Find patterns in source code, identify function calls, variable names
Regex Flags Explained
- g (global): Find all matches instead of stopping after the first match
- i (case insensitive): Match both uppercase and lowercase letters
- m (multiline): ^ and $ match start/end of each line, not just the string
- s (dotall): Dot (.) matches newline characters too
- u (unicode): Enable full unicode support for matching
Frequently Asked Questions
How do I escape special characters in regular expressions?
To match literal characters that have special meanings in regex (such as dots, stars, or question marks), prepend them with a backslash. For example, use \\. to match a literal dot character.
What are capturing groups in regex?
Capturing groups are defined by placing patterns inside parentheses (). They allow the regex engine to remember and isolate specific segments of the matched string for extraction or replacement.
Why isn't my pattern matching?
Common issues: forgetting to escape special characters, incorrect quantifiers, wrong flags. Try testing with simpler patterns first and gradually add complexity.
Can I test regex for other languages?
This tool uses JavaScript regex syntax. Most regex features are similar across languages, but some advanced features may differ. Always test in your target language's environment.
How do I match Unicode characters?
Enable the 'u' (unicode) flag and use Unicode property escapes like \p{Letter}or specific ranges. The unicode flag is required for emoji and many international characters.
About This Tool
Regex Tester helps you test and validate regular expressions with live results.
The Regex Tester serves multiple important use cases across different industries and professions. Developers use it to build and test regex patterns. Data analysts use it to create data extraction rules. QA engineers use it to validate input patterns. System administrators use it for log parsing. Each of these applications benefits from the speed, accuracy, and convenience that our tool provides.
Many similar tools require account creation or subscription fees. We believe in providing value freely and openly, which is why our Regex Tester is available to everyone without registration or payment. You can bookmark this page and return anytime you need the tool without worrying about subscriptions expiring or accounts being locked.
If you encounter any issues or have questions about using the Regex Tester, our support resources are here to help. The tool includes built-in help text and examples that guide you through the process. For more complex questions, you can refer to our comprehensive documentation or contact our support team who are happy to assist you.
We welcome feedback and suggestions for improving the Regex Tester. If you have ideas for new features or encounter bugs, please let us know so we can continue enhancing the tool. Your input directly influences our development priorities and helps us create tools that better serve the community.
The Regex Tester represents our commitment to providing high-quality, accessible tools for web professionals and enthusiasts. Whether you use it occasionally or rely on it daily, we hope it makes your work easier, faster, and more effective. Thank you for choosing our tool, and we look forward to supporting your continued success.
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