Regex Tester
The online Regular Expression Tester helps you test and validate regex patterns in real-time. It supports multiple regex flags (global, case insensitive, multiline, etc.) and displays detailed match results including index, value, and group information. The tool provides a reference guide for common regex metacharacters and examples, helping you quickly build and test complex regular expressions. Suitable for development debugging, data validation, text processing, and various other scenarios.
Regex Reference
Regular expressions are patterns used to match character combinations in strings. Here are some common regex metacharacters and examples:
| Character | Description |
|---|---|
| . | Matches any single character except newline |
| \d | Matches any digit, equivalent to [0-9] |
| \D | Matches any non-digit, equivalent to [^0-9] |
| \w | Matches any word character (letter, digit, underscore), equivalent to [A-Za-z0-9_] |
| \W | Matches any non-word character, equivalent to [^A-Za-z0-9_] |
| \s | Matches any whitespace character (space, tab, newline, etc.) |
| \S | Matches any non-whitespace character |
| ^ | Matches the beginning of a string |
| $ | Matches the end of a string |
| * | Matches the preceding expression 0 or more times |
| + | Matches the preceding expression 1 or more times |
| ? | Matches the preceding expression 0 or 1 time |
| {n} | Matches the preceding expression exactly n times |
| {n,} | Matches the preceding expression at least n times |
| {n,m} | Matches the preceding expression between n and m times |
| | | Matches either the expression before or after the | |
| [] | Character class, matches any one character inside the brackets |
| [^] | Negated character class, matches any one character not inside the brackets |
| () | Capturing group, matches the expression inside and captures the result |
| (?:) | Non-capturing group, matches the expression inside without capturing |
Common Regex Patterns
Matches valid email addresses
[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}URL
Matches HTTP or HTTPS URLs
https?:\/\/[\w\-\.]+\.[a-zA-Z]{2,}(\/\S*)?Phone Number
Matches international phone numbers
\+?\d{1,4}[-.\s]?\(?\d{1,3}\)?[-.\s]?\d{1,4}[-.\s]?\d{1,4}[-.\s]?\d{1,9}Date (YYYY-MM-DD)
Matches dates in YYYY-MM-DD format
\d{4}-\d{2}-\d{2}IP Address
Matches IPv4 addresses
((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)About Regex Tester
The online Regular Expression Tester helps you test and validate regex patterns in real-time. It supports multiple regex flags (global, case insensitive, multiline, etc.) and displays detailed match results including index, value, and group information. The tool provides a reference guide for common regex metacharacters and examples, helping you quickly build and test complex regular expressions. Suitable for development debugging, data validation, text processing, and various other scenarios.
What is a Regular Expression?
A regular expression (regex) is a pattern used to match character combinations in strings. It's a powerful text processing tool that can be used for searching, replacing, validating, and extracting information from text. Regular expressions use special characters and syntax rules to define matching patterns, capable of handling various complex text matching requirements.
When to Use Regular Expressions?
- Validating user input (emails, phone numbers, password strength, etc.)
- Extracting specific formatted information from text (dates, URLs, tags, etc.)
- Searching and replacing specific patterns in text
- Data cleaning and format conversion
Features
- Support for multiple regex flags (global, case insensitive, multiline, etc.)
- Real-time display of match results, including index, value, and group information
- Reference guide for common regex metacharacters and examples
- Clean and intuitive interface for quick regex testing