How do I test a regular expression?

Enter your regex pattern in the pattern input field, paste or type your test text, select flags (global, case-insensitive, multiline, etc.), and the tool automatically shows matches in real-time with highlighting.

What regex flags are supported?

The tester supports standard JavaScript regex flags: g (global - find all matches), i (case-insensitive), m (multiline), s (dotall), u (unicode), and y (sticky). You can combine multiple flags.

Can I see captured groups?

Yes! The tester displays all captured groups for each match, showing group index, match text, and position. This helps you understand how your regex pattern captures data.

What are regex examples?

The tool includes common regex examples like email validation, URL matching, phone numbers, IP addresses, dates, hex colors, and more. Click on any example to load it and see how it works.

How do I debug regex errors?

If your regex has syntax errors, the tester displays error messages explaining what's wrong. Common issues include unclosed brackets, invalid escape sequences, or incorrect quantifiers.

Is the regex tester free to use?

Yes, completely free! No registration, no limits, no hidden fees. All regex testing happens in your browser - we never see or store your patterns or test data.

🔎 Regex Tester - Test Regular Expressions

Test and debug regular expressions online for free. Real-time matching, flag options, group capture, and syntax highlighting. Perfect for developers and programmers.

Regex Pattern

Regular Expression

Flags:

Active: g

Quick Examples:

Auto-test as you type

Test Text & Results

Test Text

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 within strings, text processing, and data validation. Regular expressions are powerful tools for developers, allowing complex text searches and replacements with concise syntax.

Our free regex tester lets you test and debug regular expressions in real-time. Enter your pattern, choose flags (global, case-insensitive, multiline, etc.), and see matches highlighted in your test text. Perfect for learning regex, debugging patterns, and validating expressions before using them in your code.

Frequently Asked Questions

What regex syntax is supported?

Our tester supports JavaScript/ECMAScript regex syntax, which is compatible with most modern programming languages. This includes character classes, quantifiers, anchors, groups, lookaheads, and more.

How do I use capturing groups?

Use parentheses () to create capturing groups. Matched groups are displayed in the results for each match.

Is my pattern or text stored?

No, all regex testing happens entirely in your browser. We never see, store, or transmit any of your patterns or test text. Your privacy is completely protected.