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Professional regex tester with real-time pattern matching, explanation, and debugging. Test regular expressions, validate patterns, and debug regex with instant feedback and visualization.

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Why Choose Our Regex Tester?

Real-time Testing

Test your regex patterns instantly as you type with live feedback and immediate results visualization.

Syntax Highlighting

Visual feedback with match highlighting, error indicators, and pattern validation to help debug your regex.

Multiple Test Modes

Match finding, find & replace, text splitting, and pattern validation - all in one comprehensive tool.

Pattern Library

Built-in library of common regex patterns for emails, URLs, phone numbers, dates, and more.

Pattern Explanation

Understand complex regex patterns with detailed explanations and breakdown of each component.

Privacy Focused

All regex testing happens locally in your browser - your patterns and text never leave your device.

Perfect For Every Use Case

Development & Programming

  • Form validation
  • Data parsing
  • Log analysis
  • Code refactoring
  • API response processing

Text Processing

  • Content cleaning
  • Format conversion
  • Data extraction
  • Search and replace
  • Text transformation

Data Validation

  • Email validation
  • Phone number format
  • Password strength
  • Credit card numbers
  • Input sanitization

Data Analysis

  • Log parsing
  • CSV processing
  • Report generation
  • Pattern recognition
  • Data mining

Regex Basics & Syntax

.
Dot
Matches any single character except newline
a.c matches "abc", "axc", "a1c"
*
Asterisk
Matches zero or more of the preceding character
ab*c matches "ac", "abc", "abbc"
+
Plus
Matches one or more of the preceding character
ab+c matches "abc", "abbc" but not "ac"
?
Question Mark
Matches zero or one of the preceding character
ab?c matches "ac", "abc" but not "abbc"
^
Caret
Matches the start of a string
^hello matches strings starting with "hello"
$
Dollar
Matches the end of a string
world$ matches strings ending with "world"
\d
Digit
Matches any digit (0-9)
\d+ matches "123", "42", "7"
\w
Word Character
Matches word characters (a-z, A-Z, 0-9, _)
\w+ matches "hello", "test123", "my_var"
\s
Whitespace
Matches whitespace characters (space, tab, newline)
\s+ matches spaces, tabs, and line breaks
[abc]
Character Class
Matches any character in the brackets
[aeiou] matches any vowel
[^abc]
Negated Class
Matches any character NOT in the brackets
[^0-9] matches any non-digit
(abc)
Capturing Group
Groups characters and captures the match
(\d{3})-(\d{3}) captures area code and prefix

Common Regex Patterns

Email Address

Validates email addresses

[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}
Example: user@example.com

URL/Website

Matches HTTP and HTTPS URLs

https?://[\w\-]+(\.[\w\-]+)+([\w\-\.,@?^=%&:/~\+#]*)
Example: https://www.example.com

Phone Number (US)

US phone number format

\(?\d{3}\)?[\s.-]?\d{3}[\s.-]?\d{4}
Example: (555) 123-4567

Date (MM/DD/YYYY)

Date in MM/DD/YYYY format

(0[1-9]|1[0-2])/(0[1-9]|[12]\d|3[01])/(19|20)\d{2}
Example: 12/31/2023

IP Address

IPv4 address format

\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b
Example: 192.168.1.1

Credit Card

Credit card number format

\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}
Example: 1234 5678 9012 3456

Regex Flags Explained

g
Global
Find all matches instead of stopping after the first match
i
Ignore Case
Make the pattern case-insensitive
m
Multiline
Make ^ and $ match line breaks
s
Dot All
Make . match newline characters
u
Unicode
Enable Unicode support
y
Sticky
Match only from the index indicated by lastIndex

Tips & Best Practices

Start Simple

Begin with basic patterns and gradually add complexity. Test each component before combining them into larger expressions.

Use Character Classes

Character classes like [a-zA-Z] are more readable and maintainable than long alternations like (a|b|c|d|...).

Escape Special Characters

Remember to escape special regex characters like . * + ? ^ $ { } [ ] \ | ( ) when you want to match them literally.

Test Edge Cases

Always test your regex with various inputs including empty strings, very long strings, and unexpected characters.

Performance Matters

Avoid catastrophic backtracking by being specific with quantifiers and using non-capturing groups (?:) when you don't need to capture.

Document Complex Patterns

Use comments and break complex patterns into smaller, named components to make them easier to understand and maintain.

Frequently Asked Questions

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, allowing you to find, extract, or replace text based on specific rules.

How do I test if my regex pattern is working?

Use our real-time regex tester! Enter your pattern and test text, and you'll immediately see matches highlighted. The tool also validates your pattern syntax and shows detailed match information.

What are capturing groups in regex?

Capturing groups are parts of a regex pattern enclosed in parentheses (). They capture and remember the matched text, allowing you to reference or extract specific parts of a match using $1, $2, etc.

When should I use the global flag?

Use the global flag (g) when you want to find ALL matches in your text, not just the first one. This is essential for operations like find-and-replace or when counting occurrences.

How can I make my regex case-insensitive?

Use the ignore case flag (i). This makes your pattern match regardless of letter case, so "hello" would match "Hello", "HELLO", or "hELLo".

What's the difference between * and + in regex?

* matches zero or more occurrences, while + matches one or more occurrences. For example, "ab*c" matches "ac" and "abc", but "ab+c" only matches "abc" and longer sequences.

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