Regex Tester and Debugger - Free Online Regular Expression Testing Tool

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Regex Tester and Debugger - Test, Validate, and Debug Your Regular Expressions Online

What is a Regex Tester and Debugger?

A Regex Tester and Debugger is a powerful online tool that allows you to test, validate, and debug regular expressions (regex) in real-time. Whether you're a developer, data analyst, or system administrator, mastering regular expressions can help you efficiently handle text processing, data validation, and pattern matching tasks.

Regular expressions are widely used in programming languages like JavaScript, Python, PHP, Perl, Ruby, and Go, as well as in command-line tools like grep, sed, awk, and bash scripts. However, creating a perfect regex can be challenging due to its complex syntax. That's where this tool comes in handy.

Key Features of the Regex Tester and Debugger

  • Real-time Matching: See your regex results as you type.

  • Error Highlighting: Get instant feedback on regex syntax errors.

  • Multiple Flags Support: Test with flags like Global (g), Case Insensitive (i), Multiline (m), Dot All (s), and Unicode (u).

  • Line-by-Line Validation: Identify which lines match your pattern and which ones contain errors.

  • Easy to Use: Simple interface for both beginners and advanced users.

How to Use the Regex Tester and Debugger

  1. Enter Your Regular Expression: Type your regex pattern in the "Regular Expression" input field.

  2. Add Test Strings: Paste your test text into the "Test String" area. Each line will be validated separately.

  3. Select Flags: Choose the appropriate flags for your regex.

  4. Click "Test Regex" to see the results.

Example 1: Validating Email Addresses

Regex Pattern:

^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$

Test String:

[email protected]
hello1example.com
[email protected]
invalid-email@com
example@domain

Expected Output:

Matched:

Unmatched:

  • hello1example.com

  • invalid-email@com

Example 2: Extracting URLs

Regex Pattern:

https?:\/\/(www\.)?[\w\-]+(\.[\w\-]+)+([\/\w\-._~:?#\[\]@!$&'()*+,;=%]*)?

Test String:

https://example.com
http://www.google.com
ftp://example.com
https://sub.domain.co.uk/path/to/page
example.com

Expected Output:

Matched:

Unmatched:

  • ftp://example.com

  • example.com

Example 3: Validating Phone Numbers

Regex Pattern:

\+?\d{1,3}[-.\s]?\(?\d{1,4}?\)?[-.\s]?\d{1,4}[-.\s]?\d{1,9}

Test String:

+1-800-555-1234
(123) 456-7890
800.555.1234
+44 20 7946 0958
555-1234
Invalid-Phone-Number

Expected Output:

Matched:

  • +1-800-555-1234

  • (123) 456-7890

  • 800.555.1234

  • +44 20 7946 0958

  • 555-1234

Unmatched:

  • Invalid-Phone-Number

Tips for Creating Effective Regular Expressions

  • Use anchors like ^ (start of line) and $ (end of line) to match specific positions.

  • Use character classes like [a-z], [A-Z], and [0-9] to specify allowed characters.

  • Use quantifiers like +, *, ?, and {n,m} to control the number of repetitions.

  • Use groups and backreferences to capture and reuse matched patterns.

  • Use flags like g, i, m, s, and u to control matching behavior.

Conclusion

Mastering regular expressions can save you time and effort when working with text data. This Regex Tester and Debugger makes it easy to test, validate, and debug your patterns before using them in your code. Give it a try and become a regex expert today!