Regex Tester - Free Online Regular Expression Tester
Test and debug regular expressions with real-time matching and highlighting. Free online regex tester for developers.
About Regex Tester
Test and debug regular expressions with real-time matching and highlighting. Perfect for developers working with pattern matching and text validation.
- Real-time regex pattern matching
- Visual highlighting of matches in text
- Support for common regex flags (g, i, m)
- Copy all matches to clipboard
- Client-side processing - patterns stay private
Common Patterns:
Email: [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}
URL: https?:\/\/[^\s]+
Phone: \d{3}-\d{3}-\d{4}
Date: \d{2}\/\d{2}\/\d{4}
About Regex Tester
Test and debug regular expressions with real-time matching and highlighting. Free online regex tester for developers. Regex Tester is a free online tool by NeXiilo — no sign-up required, and everything runs privately in your browser.
Whether you use it daily for work or occasionally for a quick task, Regex Tester gives you fast, accurate results without uploading your data anywhere.
How to Use Regex Tester
- Open the Regex Tester above — paste or enter your input.
- Adjust any options to match what you need.
- Get instant results right in your browser.
- Copy or reuse the output wherever you need it.
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Frequently Asked Questions
What is a regular expression?
A regular expression (regex) is a sequence of characters that defines a search pattern. It is used for pattern matching, validation, and text manipulation in programming.
How do I test a regex pattern?
Enter your regex pattern in the pattern field, then enter test text in the text area. The tool will highlight all matches in real-time and show match details.
What regex flags are supported?
This tool supports common flags like g (global), i (case-insensitive), m (multiline), and s (dotAll). You can toggle these flags based on your needs.
Why is my regex not matching?
Common issues include: incorrect pattern syntax, missing escape characters for special characters, wrong flags, or the pattern not matching your test text. Use the error messages to debug.
Can I use capture groups?
Yes, you can use capture groups with parentheses () to extract specific parts of matches. The tool will show all captured groups in the results.