Regex Tester
Enter a pattern and flags, then test against your text. Supports JavaScript regex syntax.
What is Regex Tester?
Regex Tester is a powerful development tool that allows you to test and validate regular expressions (regex) in real-time using JavaScript syntax. It provides an interactive environment where you can write regex patterns, test them against sample text, and see immediate results with detailed match information.
This tool supports all JavaScript regex flags including global (g), case-insensitive (i), multiline (m), dotall (s), unicode (u), and sticky (y) matching. It's essential for developers, system administrators, and anyone working with text processing, data validation, or pattern matching in their applications.
Whether you're validating user input, parsing log files, extracting data from text, or learning regex patterns, this tester helps you debug, optimize, and understand how your regular expressions work with different text inputs.
What Problems Does It Solve?
Pattern Debugging
Helps developers debug complex regex patterns by showing exactly which parts of text match and where matches occur.
Data Validation
Enables testing of regex patterns for form validation, email verification, phone number formatting, and other input validation scenarios.
Text Processing
Facilitates development of text parsing, search and replace operations, and data extraction patterns for various applications.
Learning & Education
Provides an interactive environment for learning regex syntax, understanding pattern matching, and experimenting with different expressions.
How to Use Regex Tester
Enter Test Text
Paste or type the text you want to test against in the main text area. This will be the content your regex pattern will search through.
Write Regex Pattern
Enter your regular expression pattern in the Pattern field and specify any flags (g, i, m, s, u, y) you want to use for matching.
Analyze Results
Review the match results, including the number of matches found, highlighted text, and position information for each match.
Regex Testing Best Practices:
- • Start with simple patterns and gradually add complexity to avoid overwhelming regex syntax
- • Test your regex with various input samples including edge cases and invalid data
- • Use appropriate flags (g for global, i for case-insensitive) based on your matching requirements
- • Validate regex patterns before implementing them in production code
- • Consider performance implications of complex regex patterns on large text inputs
- • Document your regex patterns with comments explaining their purpose and expected matches
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