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Regex Tester - Free Online Regex Tool

Test, debug and validate regular expressions in real time. Supports regex pattern matching with flags (global, case-insensitive, multiline), capture groups, and replace operations. All processing runs locally in your browser for complete privacy.

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How to Use Regex Tester

Quick Start Guide

1

Enter your regular expression pattern in the Pattern field (e.g., \\d+ for digits)

2

Paste or type the text you want to test against in the Test String area

3

Select regex flags (g for global, i for case-insensitive, m for multiline) as needed

4

Click 'Test' to see all matches, groups, and positions highlighted instantly

5

Use Match/Replace/Split tabs to switch between different regex operations

💡Pro Tips

✓Use online regex testers to avoid installing desktop software
✓Common patterns: \\d+ (digits), \\w+ (words), [a-z]+ (lowercase letters)
✓All regex testing happens locally in your browser for privacy
✓Copy working regex patterns directly into your code

Frequently Asked Questions

A regex tester is an online tool that lets you write and test regular expressions against sample text in real time. It shows matches, groups, and positions so you can debug and refine your regex patterns before using them in code. Regex testers support flags like g (global), i (case insensitive), and m (multiline).
Common regex patterns include: \\d+ (match one or more digits), \\w+ (match word characters), [a-zA-Z]+ (match letters), ^ and $ (start/end of string), .*? (non-greedy match), ( ) (capture groups), | (alternation/or). This online tester helps you experiment with all of them.
Regex flags modify how the pattern matching works. The 'g' flag (global) finds all matches instead of just the first. The 'i' flag (case-insensitive) makes matching ignore uppercase/lowercase differences. The 'm' flag (multiline) changes how ^ and $ work with multi-line text. You can combine flags like 'gi' to find all case-insensitive matches.
Yes, the basic regex syntax is universal across JavaScript, Python, Java, PHP, Go, and most languages. While each language has some unique extensions, the core syntax (character classes, quantifiers, anchors, groups) works the same everywhere. Test your pattern here then use it in any language.
Yes! All regex testing runs entirely in your browser using JavaScript. Your regex patterns and test text never leave your device or get sent to any server, ensuring complete privacy for proprietary code patterns and sensitive test data.

Still have questions? Check out our other tools or contact us for support.

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