About the Regex Tester
The Regex Tester helps you build, test, and debug regular expressions directly in your browser. Enter a regular expression, paste your sample text, and instantly see which characters, words, or patterns match. Live highlighting makes it easy to verify your expression before using it in your code, application, or automation workflow.
Whether you're validating user input, searching text, extracting data, or learning regular expressions, this tool provides a fast and reliable way to test regex patterns.
Why Use a Regex Tester?
Regular expressions (regex) are powerful for searching, matching, and manipulating text, but even a small mistake can produce unexpected results. Testing your expressions against sample data helps you identify errors, improve accuracy, and save time before using them in production.
The Regex Tester provides immediate visual feedback, making it easier to understand exactly what your pattern matches.
Features
- Test regular expressions instantly
- Live match highlighting
- Validate regex patterns against sample text
- Test capture groups and pattern matching
- Experiment with different expressions safely
- Fast browser-based processing
- Works on desktop, tablet, and mobile devices
- No downloads or registration required
How To Use the Regex Tester
- Enter or paste your regular expression.
- Paste your sample text into the input area.
- Run the test to view matching results.
- Review the highlighted matches.
- Modify your pattern until it produces the expected results.
Regex Examples
Match Email Addresses
Find email addresses within a block of text.
Sample Text
Contact us at support@example.com or sales@example.com
Regex Pattern
[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+.[A-Za-z]{2,}
The highlighted results show every matching email address.
Find Phone Numbers
Locate phone numbers that follow a specific format.
Sample Text
Call 555-123-4567 or 555-987-6543.
Regex Pattern
\d{3}-\d{3}-\d{4}
Useful for validating or extracting phone numbers from text.
Match Dates
Identify dates written in a consistent format.
Sample Text
Meeting dates: 2026-07-15 and 2026-08-01
Regex Pattern
\d{4}-\d{2}-\d{2}
Helpful when working with logs, reports, and structured data.
Search for Specific Words
Find every occurrence of a particular word or phrase.
Sample Text
The quick brown fox jumps over the lazy fox.
Regex Pattern
fox
This is useful for searching documents, logs, and source code.
Test Input Validation
Regular expressions are commonly used to validate user input before it is processed.
Typical validation tasks include:
- Email addresses
- Usernames
- Password rules
- Postal codes
- Phone numbers
- Product codes
- Identification numbers
Testing your regex first helps ensure it matches only the values you expect.
Common Uses
The Regex Tester is useful for:
- Software development
- Web development
- Data validation
- Form validation
- API development
- Text searching
- Data extraction
- Log analysis
- Learning regular expressions
- Debugging regex patterns
Understanding Regular Expressions
A regular expression is a sequence of characters that defines a search pattern. Regex can be used to search, match, extract, validate, or replace text in many programming languages and applications.
Regular expressions are commonly used for:
- Searching text
- Validating user input
- Extracting structured data
- Parsing log files
- Processing documents
- Automating repetitive text tasks
Testing expressions before using them helps reduce errors and ensures your patterns behave as expected.
Tips for Better Results
- Start with a simple pattern before adding complexity.
- Test your regex using realistic sample text.
- Verify that your pattern matches only the intended text.
- Check edge cases and unexpected input before using the expression in production.
- Document complex regular expressions so they're easier to understand and maintain.
Frequently Asked Questions
What does the Regex Tester do?
It lets you test regular expressions against sample text and highlights the parts of the text that match your pattern.
What is a regular expression?
A regular expression (regex) is a pattern used to search, match, validate, or manipulate text.
Can I use this tool for learning regex?
Yes. The live highlighting makes it easy to see how different patterns behave, making it useful for both beginners and experienced developers.
Can I test input validation patterns?
Yes. The Regex Tester is commonly used to test patterns for email addresses, usernames, phone numbers, passwords, and many other types of user input.
Does the tool modify my text?
No. It only tests your regular expression against the sample text and displays the matching results.
Is my data stored?
No. Your regular expressions and sample text are processed within your browser and are not stored or shared.
Is the Regex Tester free?
Yes. You can test and debug regular expressions online for free without creating an account or downloading software.