Test JavaScript regular expressions against sample text with highlighted matches, capture details, and token-by-token explanations. Runs locally in your browser.

How to use this tool

1. Enter the pattern (without surrounding slashes unless you need them in the pattern). 2. Paste sample text. 3. Review matches, groups, and the explanation. 4. Iterate until captures match the fields you expect.

Worked example

Example: pattern (\d{3})-(\d{2})-(\d{4}) on 123-45-6789 highlights the full match and three capture groups for area, group, and serial.

How it works

Enter a regular expression and sample text to debug matches, capture groups, highlighted output, and token-by-token explanations. Everything runs locally in your browser.

Limitations

Results are based on the inputs you provide and may not cover every edge case. This tool is for general use and is not professional advice.

Privacy and file handling

Your data stays on your device and is not uploaded.

FAQ

Frequently asked questions

Is Regex Debugger free?

Yes. It is free to use and you do not need to sign in or create an account.

Is my data private?

See the privacy note on this page. Many tools run on your device; some heavier file tools may use secure temporary processing when required.

Can I use Regex Debugger on mobile?

Yes. Open this page on your phone or tablet, enter your inputs, and use the on-screen controls.

Page last reviewed: March 1, 2026

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