Regex Tester & Pattern Matcher
Free online tool to test regular expressions with live matching, pattern explanations, and match highlighting. Perfect for debugging regex patterns and learning regex syntax.
👆 Enter a regex pattern and test string above
Or click "Load Example" below to see how it works. All testing happens in your browser - your data never leaves your device.
How to Use This Tool
Using our regex tester is simple. Enter your regular expression pattern in the top input field, including any flags you need (g for global, i for case-insensitive, m for multiline, etc.). Then paste or type your test text in the second field.
The tool matches your pattern against the test text in real-time. All matches are highlighted in the text preview, and detailed information about each match appears below, including position, captured groups, and the matched text. Use the flag buttons to quickly enable or disable common regex flags.
All regex testing happens entirely in your browser using JavaScript. Your patterns and test data never leave your device, ensuring complete privacy for sensitive text or proprietary regex patterns.
Common Use Cases
Regular expressions are essential for text processing, validation, and data extraction. Developers use regex testers to validate email addresses, phone numbers, and URLs, extract data from logs and text files, and build search and replace patterns for text editors and IDEs.
Common scenarios include validating user input in web forms, parsing log files to extract specific information, finding and replacing text patterns in code, validating data formats like dates and credit card numbers, and scraping structured data from HTML or text documents.
This tool is particularly useful when learning regex syntax, debugging complex patterns, testing edge cases, and understanding how capture groups work. Whether you're a frontend developer, backend engineer, or data scientist, regex testing saves time and prevents runtime errors. Pour plus d'outils pour développeurs, visitez ImageColorPro.
Why Use Our Regex Tester?
Live Matching
See matches instantly as you type. Real-time highlighting shows exactly what your pattern matches, making regex debugging fast and intuitive.
Match Details
See detailed information about each match including position, captured groups, and matched text. Perfect for understanding complex patterns.
Pattern Explanations
Learn regex syntax with automatic pattern explanations. Understand what each part of your pattern does, making regex less intimidating.
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Frequently Asked Questions
What regex flags are supported?
We support all standard JavaScript regex flags: g (global - find all matches), i (case-insensitive), m (multiline - ^ and $ match line breaks), s (dotAll - dot matches newlines), u (unicode), and y (sticky). Click the flag buttons to quickly enable or disable them.
How do I see capture groups in my matches?
Capture groups are shown automatically in the match details section. Each match displays its captured groups with their values. For example, the pattern (\d+)-(\d+)-(\d+) matching "2024-01-15" would show three capture groups: "2024", "01", and "15".
Is my test data safe when using this tool?
Yes, absolutely. All regex testing happens entirely in your browser using JavaScript. Your patterns and test data never leave your device or get sent to any server. This means you can safely test regex patterns on sensitive logs, personal data, or proprietary text without privacy concerns.
Why is my pattern not matching?
Common issues include: forgetting the global flag (g) to find all matches instead of just the first one, case sensitivity (use the i flag for case-insensitive matching), special characters that need escaping (like . * + ? ^ $ { } ( ) [ ] | \), and incorrect multiline flag settings. Check the pattern explanation section for hints about what your pattern does.
Can I test patterns with very large text?
Yes, the tester can handle large text efficiently. Since processing happens in your browser, the main limitation is your device's memory. For very large files, you may want to test on a representative sample first to ensure your pattern works correctly before processing the full file.
Do I need to sign up or pay to use this tool?
No, this tool is completely free to use with no signup required. There are no usage limits, no character restrictions, and no hidden costs. We believe developer tools should be accessible to everyone.