Regex Tester
Test regular expressions instantly against text input. Validate patterns, find matches, and debug regex expressions online.
This calculator is useful in several situations, including Email Validation, Password Validation, Form Validation, Data Extraction, Search Operations, Log Analysis, Input Validation, and Programming. In each case, it applies the correct formula automatically so you get a precise result without manual calculation.
Common flags: g (global), i (ignore case), m (multiline)
Common Regex Examples
- Email:
^[^s@]+@[^s@]+.[^s@]+$ - Numbers:
^[0-9]+$ - Letters:
^[A-Za-z]+$ - Username:
^[a-zA-Z0-9_]{3,20}$ - Strong Password:
^(?=.*[A-Z])(?=.*[0-9])(?=.*[^A-Za-z0-9]).{8,}$
Construction Calculators
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How the Regex Tester Works
Follow these simple steps to get accurate results instantly.
Enter Regex Pattern
Type or paste the regular expression pattern.
Enter Test String
Provide the text you want to test against the regex.
Run Test
Instantly view matches and validation results.
Analyze Results
See matched text, match count, and validation status.
Regex Pattern Concept
/pattern/flags
Regular expressions are patterns used to match, validate, and manipulate text. They are widely used in programming, validation, search, and parsing tasks.
Example Calculation
Input: Pattern: ^[a-zA-Z]+$ | Text: DevCalc
Output: Match Found
Common Uses
- • Email Validation
- • Password Validation
- • Form Validation
- • Data Extraction
- • Search Operations
- • Log Analysis
- • Input Validation
- • Programming
Frequently Asked Questions
Find answers to common questions about this calculator.
What Is a Regex Tester?
A Regex Tester is a developer tool used to validate and test regular expressions against sample text. Regular expressions help developers search, match, validate, and manipulate text efficiently.
What Are Regular Expressions?
Regular expressions (Regex) are text patterns used to identify specific combinations of characters within strings.
Common Regex Use Cases
- Email validation
- Password validation
- Phone number validation
- URL validation
- Data extraction
- Log file analysis
- Form validation
- Search and replace
Popular Regex Examples
| Purpose | Regex |
|---|---|
| ^[^\s@]+@[^\s@]+\.[^\s@]+$ | |
| Numbers Only | ^[0-9]+$ |
| Letters Only | ^[A-Za-z]+$ |
| Password | ^(?=.*[A-Z])(?=.*[0-9]).{8,}$ |
Why Use Our Regex Tester?
Our free Regex Tester allows developers to instantly test patterns, debug matching issues, and validate user input directly in the browser.
Written & maintained by Aditya Singh
Aditya Singh is a software engineer and the founder of DevCalc, based in Uttar Pradesh, India. He builds and maintains every calculator on this site, using standard, verified formulas — the same ones used by banks, institutions, and educators — with careful attention to accuracy. Read more about the author →