Regex Tester & Debugger
Test and debug regular expressions with real-time highlighting. Find matches, get explanations, and learn how to use regex effectively.
Regular Expression
Match Results:
Code Implementation
JavaScript
const regex = new RegExp('your_pattern_here', 'g');
const matches = myString.match(regex);Python
import re
pattern = r'your_pattern_here'
matches = re.findall(pattern, my_string)PHP
<?php
$pattern = '/your_pattern_here/m';
preg_match_all($pattern, $text, $matches);
?>Regex Patterns Library
Common patterns to help you get started. Click any pattern to use it.
Match a valid email address
^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$URL
Match a URL with optional protocol
^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$IP Address
Match an IPv4 address
^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$Phone Number
Match common phone number formats
^[\+]?[(]?[0-9]{3}[)]?[-\s\.]?[0-9]{3}[-\s\.]?[0-9]{4,6}$Date (YYYY-MM-DD)
Match a date in YYYY-MM-DD format
^\d{4}-(0[1-9]|1[0-2])-(0[1-9]|[12][0-9]|3[01])$HTML Tag
Basic HTML tag matcher
<([a-z]+)([^<]+)*(?:>(.*)<\/\1>|\s+\/>)Password Strength
Match a strong password (min 8 chars, uppercase, lowercase, number, special char)
^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$Username
Match a username (3-16 characters, alphanumeric, underscore, hyphen)
^[a-zA-Z0-9_-]{3,16}$Hex Color
Match a hex color code
^#?([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$Credit Card Number
Match major credit card numbers
^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|3[47][0-9]{13}|6(?:011|5[0-9]{2})[0-9]{12})$Regex Cheatsheet
Character Classes
\d- Match a digit\w- Match a word character\s- Match a whitespace character[abc]- Match any character in the set[^abc]- Match any character not in the set
Quantifiers
*- Match 0 or more times+- Match 1 or more times?- Match 0 or 1 time{n}- Match exactly n times{n,}- Match at least n times{n,m}- Match between n and m times
Anchors
^- Start of string/line$- End of string/line\b- Word boundary
Flags
g- Global search (find all matches)i- Case-insensitive searchm- Multi-line mode (^ and $ match line starts/ends)s- Dot (.) matches newlines
How to Use the Regex Tester
Step 1: Enter Your Pattern
Type or paste your regular expression pattern in the input field. The tool supports all standard regex syntax including character classes, quantifiers, groups, and assertions. You can also select from our library of common patterns.
Step 2: Add Test String
Enter the text you want to test against your pattern. Matches will be highlighted in real-time as you type, making it easy to see exactly what your regex is capturing.
Step 3: Configure Flags
Select the appropriate flags for your use case. Common flags include 'g' for global matching, 'i' for case-insensitive matching, and 'm' for multiline mode.
Step 4: Export Your Pattern
Once your regex is working correctly, copy it to your clipboard or generate code snippets for JavaScript, Python, PHP, and other programming languages.
Frequently Asked Questions
What is regex (regular expression)?
A regular expression (regex) is a sequence of characters that defines a search pattern. It's commonly used for string matching, validation, and text manipulation in programming and data processing.
What are regex flags?
Regex flags modify how a pattern is interpreted. Common flags include 'g' (global - find all matches), 'i' (case-insensitive), 'm' (multiline - ^ and $ match line breaks), 's' (dotall - . matches newlines), and 'u' (unicode support).
How do I match special characters?
Special characters like ., *, +, ?, [, ], {, }, (, ), |, \, ^, and $ have special meanings in regex. To match them literally, escape them with a backslash (\). For example, \. matches a literal period.
What's the difference between greedy and lazy matching?
Greedy quantifiers (*, +, ?) match as much as possible, while lazy quantifiers (*?, +?, ??) match as little as possible. For example, .* is greedy and will match everything it can, while .*? is lazy and stops at the first opportunity.
Can I use this tool for email validation?
Yes! We provide a pre-built email validation pattern in our Common Patterns library. However, note that complete email validation is complex - for production use, consider using dedicated email validation libraries.
Regex Tester Features
Real-Time Testing
See matches highlighted instantly as you type. No need to click a button - the regex engine processes your patterns in real-time.
Code Generation
Generate ready-to-use code snippets for JavaScript, Python, PHP, and other languages with proper escaping and syntax.
Pattern Library
Access a curated collection of common regex patterns for emails, URLs, phone numbers, and more. Learn by example.