RegEx Tester
Test and debug regular expressions with real-time matching and highlighting. Perfect for developers working with form validation, text parsing, or data extraction.
Flags
Sample Patterns
Results
Highlighted Matches
About the RegEx Tester
The RegEx Tester is a powerful tool for creating, testing, and debugging regular expressions. Whether you're validating form inputs, parsing text, or extracting data patterns, this tool helps you visualize and refine your regular expressions in real-time.
What are Regular Expressions?
Regular expressions (regex or regexp) are sequences of characters that define a search pattern. They are used for pattern matching within strings and are supported in most programming languages. Regular expressions can be simple, like finding all occurrences of a specific word, or complex, like validating email addresses or extracting structured data from text.
Features of Our RegEx Tester
Real-time Testing
See your regex matches instantly as you type, with visual highlighting of matched text and capture groups. This immediate feedback helps you quickly refine your patterns.
Capture Group Extraction
View all captured groups separately, making it easy to understand how your regex is breaking down the text and extracting specific components.
Regex Flags Support
Toggle various regex flags like global (g), case-insensitive (i), multiline (m), and others to modify how your pattern behaves when matching text.
Common Pattern Library
Access a library of commonly used regex patterns for emails, URLs, phone numbers, dates, and more. Use these as starting points for your own patterns.
Common RegEx Use Cases
- Form validation - Ensure user inputs match required formats (emails, passwords, phone numbers)
- Data extraction - Pull specific information from unstructured text or logs
- Search and replace - Find and modify text patterns in documents or code
- Text parsing - Break down complex strings into meaningful components
- URL routing - Match URL patterns in web applications
- Syntax highlighting - Identify code elements for proper formatting
RegEx Quick Reference
| Symbol | Description | Example |
|---|---|---|
. | Matches any character except newline | a.c matches "abc", "adc", etc. |
^ | Matches start of string | ^hello matches "hello world" |
$ | Matches end of string | world$ matches "hello world" |
* | 0 or more occurrences | ab*c matches "ac", "abc", "abbc", etc. |
+ | 1 or more occurrences | ab+c matches "abc", "abbc", but not "ac" |
Pro Tip
When working with complex regular expressions, build them incrementally. Start with a simple pattern that matches part of what you need, then gradually add complexity while testing at each step. This approach makes it easier to identify and fix issues.