Is Regex Tester free?

Yes, all tools provided by WebTools are completely free to use with no signup required.

Is Regex Tester safe?

Absolutely safe. All data processing happens locally in your browser. Nothing is uploaded to any server, ensuring your privacy is fully protected.

Do I need to install software to use Regex Tester?

No installation needed. All tools run in your browser - just open the page and start using them immediately.

What is a regular expression?

A regular expression (regex) is a sequence of characters that defines a search pattern. It's used for pattern matching, text validation, search and replace, and data extraction in programming and text processing.

What are regex flags?

Flags modify how the regex engine processes the pattern. Common flags: g (global — find all matches), i (case-insensitive), m (multiline — ^ and $ match line boundaries), s (dotAll — . matches newlines).

What are captured groups?

Captured groups are portions of the match enclosed in parentheses (). They allow you to extract specific parts of the matched text. Groups are numbered from left to right and can be accessed in replacement patterns.

Which regex flavor does this tool use?

This tool uses JavaScript's built-in RegExp engine, which follows the ECMAScript specification. It supports most common regex features including character classes, quantifiers, anchors, lookaheads, and named groups.

Can I use this for regex replacement?

This tool focuses on testing and debugging regex patterns. For find-and-replace operations, use the Text Replace tool which supports regex-based replacement.

Regex Tester

Regex Tester is a free online tool that helps you test and debug regular expressions in real time. Type your pattern and test string, see matches highlighted instantly, view captured groups, and reference the built-in cheat sheet — no signup, no installation, completely private.

Regular Expression

g=Globali=Case-insensitivem=Multilines=DotAll

Common Patterns

Test String

Match Results0 match(es)

No matches found

What is Regex Tester?

Real-time regex matching as you type
Visual highlighting of all matches in the test string
Captured groups display with indices
Regex flags support (global, case-insensitive, multiline, dotAll)
Built-in regex cheat sheet for quick reference
Match count and match details panel
All processing happens locally in your browser

How to Use Regex Tester

1
Enter your regex pattern
Type your regular expression pattern in the pattern input field.
2
Set regex flags
Toggle flags like g (global), i (case-insensitive), m (multiline), and s (dotAll).
3
Enter test string
Type or paste the text you want to test your regex against.
4
Review matches
Matches are highlighted in real time. View captured groups and match details in the results panel.

Frequently Asked Questions

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