Regex Tester Tool
Regex Tester Tool
Test, debug and visualize regular expressions in real-time with match highlighting and detailed results
Match Results
About Regular Expressions (Regex)
Regular expressions are powerful patterns used to match, search, and manipulate text. They are supported in most programming languages and text editors, making them an essential tool for developers.
Why Use Regex?
Regex allows you to:
- Validate input formats (emails, phone numbers, passwords)
- Extract specific information from text (dates, numbers, URLs)
- Search and replace text with complex patterns
- Parse and process structured data like logs or CSV files
- Split strings based on complex delimiters
Common Regex Patterns
Email Validation
\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b
Matches standard email addresses
Phone Numbers
(\+\d{1,3}\s?)?\(?\d{3}\)?[\s.-]?\d{3}[\s.-]?\d{4}
Matches various phone number formats
Username Check
^[a-zA-Z0-9_]{3,16}$
3-16 characters, letters, numbers, underscores
Extract Numbers
\d+
Matches one or more digits
URL Pattern
https?://(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)
Matches HTTP/HTTPS URLs
Date (YYYY-MM-DD)
\d{4}-\d{2}-\d{2}
Matches dates in YYYY-MM-DD format
How to Use This Tool
- Enter your regex pattern in the "Regular Expression" field
- Enter text to test against in the "Test String" field
- Select appropriate flags for your pattern (global, case-insensitive, etc.)
- Click "Test Regex" to see matches highlighted in real-time
- View match count and detailed match information below
- Use "Copy Results" or "Download" to save your matches
Tips for Beginners
- Start simple - Begin with basic patterns like
\dfor digits or\wfor word characters - Use anchors -
^matches start of string,$matches end - Quantifiers -
*(0 or more),+(1 or more),?(0 or 1),{n,m}(between n and m) - Character classes -
[a-z]matches any lowercase letter,[0-9]matches digits - Escaping - Use
\before special characters to match them literally (e.g.,\.matches a period) - Test incrementally - Build your pattern step by step, testing as you go
Safety Note
Regex can be complex and may have performance implications with certain patterns (like catastrophic backtracking). Always test your expressions with various inputs, especially when using them in production systems.
This Regex Tester tool helps developers validate and debug regular expressions with real-time feedback and detailed match information. Perfect for testing email validation, phone number patterns, data extraction, and text processing tasks.
What Is the Regex Tester Tool?
The Regex Tester Tool is a powerful online utility for creating, testing, and debugging regular expressions. Regular expressions (regex) are patterns used to match character combinations in strings, and this tool provides an interactive environment to work with them efficiently, solving the problem of complex pattern matching and text processing.
Whether you're validating user input, searching through logs, extracting data from text, or performing complex text transformations, our Regex Tester helps you build and test patterns in real-time with immediate feedback, making regex development faster and more reliable.
Why Use the Regex Tester Tool?
Regex is essential for text processing, data validation, and automation tasks. This tool is particularly valuable for:
Developers & Programmers
Write and debug regex patterns for programming languages like JavaScript, Python, Java, PHP, and C#
Data Analysts
Extract, clean, and validate data from text files, logs, and databases using pattern matching
System Administrators
Search through log files, filter command outputs, and automate text processing tasks
QA Engineers
Create validation patterns for testing form inputs, API responses, and data formats
Technical Writers
Search and replace patterns in documentation, format text, and process documentation files
Students & Educators
Learn regex syntax, practice pattern matching, and understand text processing concepts
How to Use the Regex Tester Tool on All Unit Tools
Testing and debugging regular expressions is straightforward with our interactive interface:
/.*/ Enter Pattern
Type your regular expression pattern in the regex input field. Use the cheat sheet for common patterns and syntax reference.
๐ Input Test Text
Paste or type the text you want to test against your regex pattern. You can use sample texts or your own content.
⚡ Test & Debug
Click "Test" to see matches highlighted in real-time. Use the debug panel to understand how your pattern works step by step.
⚙️ Configure Flags
Set regex flags like case-insensitive (i), global (g), multiline (m), and others to modify matching behavior.
Key Features of the Regex Tester Tool
Real-time Matching
See matches highlighted immediately as you type, with different colors for capture groups
Multi-language Support
Test regex patterns compatible with JavaScript, Python, PHP, Java, C#, and other programming languages
Cheat Sheet
Quick reference for regex syntax, character classes, quantifiers, anchors, and common patterns
Match Details
Detailed breakdown of each match including position, length, and captured group values
Replace Function
Test search-and-replace operations with capture group references ($1, $2, etc.)
Sample Library
Pre-built patterns for common tasks like email validation, phone numbers, URLs, and dates
Common Use Cases
Form Validation
Validate email addresses, phone numbers, passwords, dates, and other user input formats
Data Extraction
Extract specific information from text files, logs, HTML, JSON, or other structured data
Text Processing
Search and replace operations, formatting text, cleaning data, andๆน้ text transformations
Log Analysis
Parse and filter server logs, application logs, and system monitoring outputs
Code Refactoring
Find and replace patterns in code files, rename variables, or refactor code structure
Content Analysis
Analyze text content, count occurrences, extract keywords, or identify patterns in documents
Frequently Asked Questions
What's the difference between greedy and lazy quantifiers?
Greedy quantifiers (like *, +, {}) match as much as possible, while lazy quantifiers (like *?, +?, {}?) match as little as possible. For example, /a.*b/ on "axxxbxxxb" matches the entire string, while /a.*?b/ matches only "axxxb".
How do I match special characters literally?
Use the backslash (\) to escape special characters. For example, to match a literal dot, use \. instead of . (which matches any character). Common characters that need escaping are: . * + ? ^ $ { } [ ] ( ) | \ /
What are regex flags and when should I use them?
Flags modify regex behavior: i (case-insensitive), g (global - find all matches), m (multiline - ^ and $ match start/end of lines), s (dotall - . matches newlines), u (unicode).
Can I test regex for different programming languages?
Yes! Our tool supports regex flavors for JavaScript, Python, PHP, Java, C#, Ruby, and Perl. While basic patterns work across most languages, some advanced features and syntax may differ. We highlight language-specific differences in our cheat sheet.
How do I create a regex for email validation?
Email validation regex can be complex. A good basic pattern is: /^[^\s@]+@[^\s@]+\.[^\s@]+$/. However, for production use, consider more comprehensive patterns or use dedicated validation libraries, as email specifications are quite complex.
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