What regex flavour does this use?

JavaScript's built-in RegExp engine, which supports ES2024 features like lookbehind assertions.

Can I test with flags like global and case-insensitive?

Yes — toggle g, i, m, s, u, and y flags using the checkboxes.

Yes. The breakdown panel shows a human-readable explanation of each part of your pattern.

Paste multiple lines and enable the multiline (m) flag to test each line separately.

Test and debug regular expressions with real-time matching. Works in your browser. Free, no signup.

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Regular Expression

How useful is Regex Tester?

Enter your regular expression pattern in the top field

Type or paste test text in the input area below

View real-time matches highlighted in the text

Check the match details panel for captured groups and indices

Format and beautify JSON data with syntax highlighting.

Validate JSON syntax and find errors instantly.

Create beautiful CSS gradients visually and copy the code.

Pick colors from any format and convert between HEX, RGB, HSL.

Generate placeholder text for designs and mockups.

Format and indent HTML code for better readability.