Which regex engine does this use?

This tester uses the browser's JavaScript RegExp engine. Some features differ from PCRE or other flavors.

Yes. All testing is done locally in your browser. Nothing is sent to our servers unless you export patterns manually.

Can I save frequently used patterns?

Yes. Save and load regex patterns locally in your browser, and export/import them as JSON files.

Regex Tester & Debugger

Build, test, and debug regular expressions with live visual feedback.

gim

Save Pattern

Library

Test Subject

0 matches found

Live Preview

High-performance regex testing in the browser.\nTry matching words or 123 numbers!

Refactor & Export

Replacement Value

$1, $2 for groups • $& full match

Substitution Result

High-performance regex testing in the browser.\nTry matching words or 123 numbers!

Regex Tester & Debugger

Test and debug regular expressions with live highlighting, group inspection, replace-preview, and pattern management - all in your browser.

How to use the tool

Enter a pattern. Type your regex in the pattern field. Use flags to control behavior (g,i,m,s,u,y).
Paste test text. The tester highlights all matches and shows capture groups live.
Use replace. Test replacement strings using $1, $2, $& and preview the output before applying.
Save patterns. Save commonly used regexes locally and export them for sharing or backup.

Frequently Asked Questions

Which regex engine does this use?: This tester uses JavaScript's RegExp engine in the browser. Behavior may vary for PCRE, Python, or other flavors.
Is my data private?: Yes - all testing runs locally; nothing is uploaded unless you export patterns.
Can I save patterns?: Yes - save, load, export and import patterns using JSON files.

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