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.

Regex Tester | Conversores Online

Regex Tester

Test and debug regular expressions in real-time.

Regular Expression

Test String

Highlighted Matches

You can reach me at test@example.com or contact@another-domain.co.uk.

Match Information

2 matches found.

test@example.com
Index: 20
contact@another-domain.co.uk
Index: 40

How 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