Regex Tester
Test and debug regular expressions in real-time.
test@example.com
Index: 20
contact@another-domain.co.uk
Index: 40
- Enter your Pattern: Type your regular expression pattern in the first input field (without the slashes).
- Add Flags: Enter any regex flags (like `g` for global, `i` for case-insensitive) in the small flags input field.
- Provide a Test String: Paste or type the text you want to test your regex against in the 'Test String' area.
- See Live Results: The tool will instantly update, highlighting all matches in your test string and listing them individually. Any regex errors will be shown immediately.
help_outlineHow to Use the Free Online Regex Tester
Enter your Pattern: Type your regular expression pattern in the first input field (without the slashes).
Add Flags: Enter any regex flags (like `g` for global, `i` for case-insensitive) in the small flags input field.
Provide a Test String: Paste or type the text you want to test your regex against in the 'Test String' area.
See Live Results: The tool will instantly update, highlighting all matches in your test string and listing them individually. Any regex errors will be shown immediately.
Frequently Asked Questions
What is a regular expression (regex)?
A regular expression is a sequence of characters that specifies a search pattern in text. It's a powerful tool used by programmers to find, replace, and validate strings. For example, you can use regex to check if an email address is in a valid format.
Is this free online regex tester secure?
Yes. All testing and matching happens directly in your browser. Your regex patterns and test strings are never sent to our servers, ensuring your data remains completely private.
What do the 'g' and 'i' flags mean?
The `g` flag stands for 'global search', which means the regex will find all matches in the string, not just the first one. The `i` flag stands for 'case-insensitive', which means it will match both upper and lower case letters.
About the Regex Tester
What is the Regex Tester?
Our Regex Tester is a powerful online tool designed for testing and debugging regular expressions in real-time. Whether you're a seasoned developer crafting complex pattern matching for data validation, or just learning the ropes of regex for simple string manipulation, our tester provides an instant feedback loop. Use it to validate patterns for email addresses, phone numbers, IP addresses, URLs, or any other text-based data you need to extract or manipulate. It supports various regex flavors and options, allowing you to experiment with different syntaxes and ensure your expressions work exactly as intended before implementing them in your code (e.g., in JavaScript, Python, or PHP).
How Does It Work?
Using our Regex Tester couldn't be simpler. Just paste your regular expression into the designated "Pattern" field and then enter the text you want to test against the regex in the "Text" field. As you type, the results are instantly updated, highlighting matches and displaying detailed information such as captured groups. No need to run scripts or compile code – the entire process happens live within your browser, allowing you to quickly iterate and refine your expressions until they are perfect. This immediate feedback significantly speeds up the debugging process and reduces the frustration often associated with building complex regular expressions.
Key Benefits of Using Our Online Tool
- Real-Time Feedback: See matches and captured groups instantly as you type, eliminating the need for repeated testing and debugging cycles.
- Improved Accuracy: Ensure your regular expressions are working correctly before deploying them in your applications, reducing the risk of errors and unexpected behavior.
- Enhanced Learning: A great tool for learning regular expressions, allowing you to experiment with different patterns and see the results immediately. Ideal for understanding concepts like quantifiers, character classes, and lookarounds.
- Time Savings: Quickly identify and fix errors in your regular expressions, saving you valuable time and resources.
Is it Legal and Safe?
Absolutely. Our Regex Tester operates entirely within your web browser. This means that all processing is done locally on your computer, and your data (both the regular expression and the text you are testing) never leaves your device. We do not store or transmit any of the information you input. This ensures complete privacy and security. You can confidently use our tool to test even sensitive data without worrying about data breaches or privacy violations. The tool is designed to comply with all relevant privacy regulations.
Why Choose Our Regex Tester?
Lightning Fast
Instant results — no waiting, no queues, no page reloads.
Works on All Devices
Phone, tablet, or desktop — same smooth experience everywhere.
High Quality Output
No watermarks, no artificial limits. Pure, accurate results every time.
100% Secure & Private
No login required. Files processed in-browser — never sent to our servers.