Regex Tester - Test Regular Expressions Online

A regular expression (regex) is a sequence of characters that define a search pattern. It's used for pattern matching within strings, allowing you to search, validate, and manipulate text based on complex rules. Regex is widely used in programming, text editing, and data processing.

Using the Regex Tester is simple:

• Enter your test text in the 'Test String' area
• Type your regex pattern in the 'Pattern' field
• Select any flags you need (global, case-insensitive, etc.)
• The tool will automatically highlight all matches in real-time
• View detailed match information including capture groups and positions
• Use example patterns to learn common regex patterns

Regex flags modify how the pattern matching works. Common flags include: Global (g) finds all matches instead of just the first one, Case Insensitive (i) ignores uppercase/lowercase differences, and Multiline (m) makes ^ and $ match line boundaries. Choose flags based on your specific matching needs.

Our tool includes several common patterns like email validation, phone numbers, URLs, IP addresses, dates, and more. Click any example to load it and see how it works. These patterns can be used as-is or modified to fit your specific requirements.

Yes, absolutely! All regex testing happens entirely in your browser using JavaScript. Your test text and patterns never leave your device or get sent to any servers. This ensures complete privacy and security while also providing instant results without any network delays.

Yes! Our Regex Tester fully supports capture groups, lookaheads, lookbehinds, and other advanced regex features. When your pattern includes capture groups, they'll be displayed separately for each match, making it easy to see exactly what each group captured.

This is particularly useful when you need to extract specific parts of a match, like extracting the domain from an email address or the area code from a phone number.

Start with our example patterns to see how basic regex works. Common patterns include \d for digits, \w for word characters, . for any character, * for zero or more, + for one or more, and ? for optional. Try modifying the examples to see how changes affect the matches.

The real-time feedback from our tester makes it easy to experiment and learn. As you modify patterns, you'll immediately see how they affect the matches, making the learning process much more intuitive.