Can I test a regex written for Python in JavaScript on regex101?

The site supports PCRE2, JavaScript, Python, Go, Java, .NET, and Rust. Choose the flavor that matches your target language for accurate results.

How do I read the explanation of my regex on regex101?

The Explanation pane provides a breakdown of each component in your regex, with links to a Quick Reference for common patterns.

Is there a way to save and share a tested regex pattern?

You can save your pattern, test string, and settings to a shareable URL, or export matches, substitutions, and benchmark data for external use.

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Regex Tester

Provided byregex101regex101.com

Tests regular expressions across PCRE, JavaScript, Python, Go, Java, .NET, and Rust flavours with live highlighting, ...

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Screenshot of Regex Tester on regex101 — regex101.comOpen the live tool →

About this tool

What Regex Tester does

Regex Tester is a web-based tool for building, testing, and debugging regular expressions. Users input a pattern and test string to see matches highlighted in real time, with capture groups and substitutions displayed. The result includes a detailed breakdown of each match, making it easy to verify that a pattern works as intended before deploying it in code. What sets regex101 apart is its multi-language flavor selector and built-in reference library. The interface lets you choose between PCRE2, JavaScript, Python, Go, Java, .NET, and Rust, so the pattern syntax matches the target language. As you type, an automatic explanation generates definitions for tokens, anchors, quantifiers, and character classes. A Quick Reference pane lists common patterns, and the site also offers linked tools like a Regex Debugger, Code Generator, and Benchmark suite, all within the same workspace.

Step by step

How to use the regex101 Regex Tester

1
Open regex101 and select the regex flavor that matches your target programming language.
2
Enter your regular expression pattern in the top editor pane.
3
Paste or type the test string you want to check below the pattern.
4
Review the live highlight of matches and the Match Information panel for details on each capture group.
5
Use the Explanation or Quick Reference panes to understand or adjust the pattern syntax.

Is it right for you

Best for

Developers and IT professionals who need to test and debug regular expressions across multiple programming languages with clear, automatic explanations.

Limitations

Pattern syntax varies by selected flavor, so results may not transfer verbatim to all languages.
The free version includes sponsored links and ads on the page.
Very complex patterns or very large test strings can slow the live highlighting.

Questions

Regex Tester FAQ

Can I test a regex written for Python in JavaScript on regex101?: The site supports PCRE2, JavaScript, Python, Go, Java, .NET, and Rust. Choose the flavor that matches your target language for accurate results.
How do I read the explanation of my regex on regex101?: The Explanation pane provides a breakdown of each component in your regex, with links to a Quick Reference for common patterns.
Is there a way to save and share a tested regex pattern?: You can save your pattern, test string, and settings to a shareable URL, or export matches, substitutions, and benchmark data for external use.

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