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🔍 RegEx Validator & Tester

Professional Regular Expression Testing & Code Generation Tool

🧪 RegEx Tester

📜 JavaScript
🐍 Python
☕ Java
🔷 C#
💎 Ruby
🔥 Go
🦀 Rust
📦 Export All

💻 Code Examples

Generated code examples for your regex pattern in different programming languages:

📚 Common Patterns Library

Click on any pattern to use it in the tester above:

Email Address
^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$
Validates email addresses
Phone Number
^\+?[1-9]\d{1,14}$
International phone number format
Strong Password
^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$
Min 8 chars, uppercase, lowercase, number, special char
URL/Website
^https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)$
HTTP/HTTPS URLs validation
Date (YYYY-MM-DD)
^\d{4}-\d{2}-\d{2}$
Date in ISO format
Hex Color
^[0-9a-fA-F]{6}$
6-digit hexadecimal color codes
IP Address
^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$
IPv4 address format
Letters Only
^[A-Za-z]+$
Only alphabetic characters
Numbers Only
^\d+$
Only numeric characters
Alphanumeric
^[A-Za-z0-9]+$
Letters and numbers only
Word Extraction
\b\w+\b
Matches individual words
Length 3-20
^.{3,20}$
String length between 3 and 20 characters
Basic Password
^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)[A-Za-z\d]{6,}$
Minimum 6 chars with uppercase, lowercase, and number
Social Security Number
^\d{3}-\d{2}-\d{4}$
US SSN format (XXX-XX-XXXX)
Credit Card
^\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}$
16-digit credit card number with optional spaces or dashes
UK Postcode
^[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][ABD-HJLNP-UW-Z]{2}$
UK postal code format (e.g., SW1A 1AA)
US ZIP Code
^\d{5}(-\d{4})?$
US ZIP code (5 digits or ZIP+4 format)
Time Format
^([01]?[0-9]|2[0-3]):[0-5][0-9](:[0-5][0-9])?$
24-hour time format (HH:MM or HH:MM:SS)
Domain Name
^[a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.[a-zA-Z]{2,}$
Valid domain name format
UUID
^[A-Fa-f0-9]{8}-[A-Fa-f0-9]{4}-[A-Fa-f0-9]{4}-[A-Fa-f0-9]{4}-[A-Fa-f0-9]{12}$
Universal Unique Identifier format
Full Name
^[a-zA-Z\s]+$
Names with letters and spaces only
Currency Amount
^\$?[0-9]{1,3}(,[0-9]{3})*(\.\d{1,2})?$
Currency format with optional $ and commas
Username
^[a-zA-Z0-9_-]+$
Alphanumeric usernames with underscores and hyphens
US Date (MM/DD/YYYY)
^(0[1-9]|1[0-2])\/(0[1-9]|[12]\d|3[01])\/(19|20)\d{2}$
US date format MM/DD/YYYY
International Phone
^\+?[1-9]\d{1,14}$
International phone number with optional +
Extract Emails
\b([A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,})\b
Extract email addresses from text
Extract URLs
(https?|ftp):\/\/[^\s\/$.?#].[^\s]*
Extract HTTP, HTTPS, and FTP URLs from text

🎯 Complete RegEx Guide

What is a Regular Expression?

Regular expressions (RegEx) are powerful pattern-matching tools used for validating, searching, and manipulating text. Our RegEx validator helps you test patterns instantly with real-time feedback and multi-language code generation.

Common Use Cases

  • Email Validation: Verify email address formats
  • Phone Numbers: Validate international phone formats
  • Data Extraction: Parse logs and structured text
  • Input Sanitization: Clean user input data
  • Search & Replace: Complex text transformations

Supported Languages

Generate optimized code for JavaScript, Python, Java, C#, Ruby, Go, and Rust with proper syntax and best practices for each language.

Key Features

  • Real-time Testing: Instant pattern validation
  • Syntax Highlighting: Visual match highlighting
  • Code Generation: Multi-language code export

Advanced RegEx Techniques

Lookahead & Lookbehind

Use positive lookahead (?=...) and negative lookahead (?!...) to match patterns based on what follows. Lookbehind assertions (?<=...) and (?<!...) check what precedes the match.

Capture Groups

Parentheses () create capture groups to extract specific parts of matches. Use non-capturing groups (?:...) when you need grouping without capturing.

Character Classes

Square brackets [...] define character sets. Use ranges like [a-z], [0-9], or negate with [^...] to match anything except specified characters.

Quantifiers

Control repetition with * (zero or more), + (one or more), ? (zero or one), {n} (exactly n), {n,} (n or more), {n,m} (between n and m).

Common RegEx Patterns Explained

Email Validation

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

Matches valid email addresses with alphanumeric characters, common symbols, domain names, and top-level domains of 2+ characters.

Phone Numbers

^\+?[1-9]\d{1,14}$

International phone format with optional country code (+), starting with 1-9, followed by 1-14 digits total.

URL Validation

^https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b

Validates HTTP/HTTPS URLs with optional www, domain names up to 256 characters, and various URL-safe characters.

Password Strength

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$

Ensures passwords have at least 8 characters with lowercase, uppercase, digit, and special character requirements.

Performance Tips & Best Practices

Optimization Strategies

  • Anchor patterns: Use ^ and $ to avoid unnecessary searching
  • Specific before general: Put specific alternatives first in OR groups
  • Avoid catastrophic backtracking: Be careful with nested quantifiers
  • Use atomic groups: (?>...) prevents backtracking when possible

Testing Guidelines

  • Test edge cases: Empty strings, special characters, unicode
  • Validate inputs: Always validate user input against expected patterns
  • Consider localization: Different regions may have different formats
  • Performance testing: Test with large texts to ensure efficiency

Security Considerations

  • Input sanitization: RegEx alone isn't sufficient for security
  • ReDoS attacks: Avoid patterns vulnerable to denial of service
  • Escape user input: When building patterns from user data
  • Validate server-side: Never trust client-side validation alone

Language Differences

  • Flavor variations: PCRE, POSIX, JavaScript have differences
  • Unicode support: Varies between implementations
  • Escape sequences: \Q \E literal quoting in some flavors
  • Named groups: (?P<name>...) syntax varies by language

Real-World Applications

Web Development

Form validation, URL routing, template processing, and content parsing. RegEx is essential for validating user inputs, processing markdown, and extracting data from HTML/XML documents.

Data Processing

Log file analysis, CSV parsing, data cleaning, and format conversion. Extract structured information from unstructured text data, clean datasets, and transform data formats.

System Administration

Configuration file parsing, log monitoring, automated scripting, and system diagnostics. Parse configuration files, monitor system logs for errors, and automate routine maintenance tasks.

Text Editors & IDEs

Search and replace operations, syntax highlighting, code refactoring, and find/replace across projects. Most modern editors support RegEx for powerful text manipulation and code analysis.

Master Regular Expressions with Our Comprehensive Tool

Whether you're a beginner learning pattern matching or an expert developer optimizing complex expressions, our RegEx validator provides the tools and insights you need to work efficiently with regular expressions.

Professional regex testing • Multi-language code generation • Comprehensive pattern library • Real-time validation

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