Regex Tester
Test and debug regular expressions with live matching and highlighting.
How to Use
Enter regex
Type your regular expression pattern.
Enter test string
Paste the text you want to test against.
View matches
See highlighted matches and capture groups.
Features
Frequently Asked Questions
A regular expression (regex) is a sequence of characters that defines a search pattern. It's used for string matching and text manipulation.
Regular expressions are one of the most powerful text-processing tools in a developer's arsenal. Our regex tester provides real-time matching, syntax highlighting, and detailed explanations to help you craft and debug patterns with confidence. Test against multiple inputs simultaneously.
Did You Know?
Regular expressions were developed by mathematician Stephen Kleene in the 1950s. The term 'regex' became popular with Unix text processing tools in the 1970s!
Pro Tips
- Use \d for digits, \w for word characters, \s for whitespace
- The ? makes the preceding quantifier lazy (non-greedy)
- Use capturing groups () to extract specific parts of matches
- Test edge cases: empty strings, special characters, unicode
Common Use Cases
- Validating email addresses and phone numbers
- Extracting data from log files
- Search and replace operations in code editors
- Parsing structured text like CSV or URLs
- Form validation in web applications
Best Practices
- Comment complex regex patterns for maintainability
- Use named capture groups for readability
- Avoid catastrophic backtracking with careful pattern design
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