Online Regular Expression Checker

Test and debug regular expressions with real-time highlighting and detailed match analysis.

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< 15ms

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100%

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4.9 / 5.0

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About This Tool

This online regular expression checker allows you to test and validate regex patterns against any text input. It provides real-time match highlighting, detailed group capture information, flag customization (global, case-insensitive, multiline, etc.), and replacement functionality. The tool helps developers debug complex regex patterns with visual feedback and comprehensive results.

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How to Use

Enter your regular expression pattern in the first input field.
Enter the text you want to test against in the second input field.
Select any regex flags you need (like global, case-insensitive).
Click 'Test Regex' to see matches highlighted in real-time.
View detailed results including match count, groups, and positions.
Optionally use the replacement feature to modify the text based on your pattern.

Frequently Asked Questions

Find Quick Answers

What regex features does this tool support?

The tool supports standard JavaScript regex syntax including character classes, quantifiers, groups, lookaheads/lookbehinds, and common flags (g, i, m, s, u, y).

Can I save my regex patterns?

Patterns are processed client-side in your browser, so they're not saved on our servers. You can bookmark the page with your pattern in the URL or copy it manually.

Does this tool work with very large texts?

Yes, the tool processes text entirely in your browser, so it can handle large documents limited only by your device's memory and performance.

What browsers are supported?

The tool works in all modern browsers that support JavaScript ES6+ including Chrome, Firefox, Safari, and Edge.

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