The Regex Validator is a powerful tool designed for both beginners and experts to validate and understand regular expressions swiftly. By testing regex patterns against sample strings, users receive instant feedback and can visualize matches, making regex a more approachable and efficient process.
RegEx Validator
Pattern Breakdown
Results
How to Use the Regex Validator
Step 1: Enter Your Regex Pattern
Input your regex pattern in the RegEx Pattern field. Common examples include:
^[a-z]+$for matching lowercase letters only\d{3}-\d{2}-\d{4}for validating US Social Security numbers^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$for email validation
Step 2: Configure Regex Flags
Select appropriate flags from the dropdown menu:
- g (global): Finds all matches throughout the string, not just the first occurrence
- i (case-insensitive): Ignores letter case when matching
- m (multiline): Treats
^and$as matching line boundaries instead of string boundaries - s (dotall): Allows
.to match newline characters - u (unicode): Enables full Unicode matching support
Step 3: Enter Your Test String
In the Test String textarea, input the text you want to validate against your regex pattern. You can test multiple lines or various examples to ensure your pattern works correctly.
Step 4: Analyze Results
The tool automatically provides:
- Pattern Breakdown: Detailed explanation of each regex component
- Match Results: Visual highlighting of all matches in your test string
- Match Groups: Display of captured groups if your pattern includes parentheses
Practical Example
📱 Example Usage
^\(\d{3}\) \d{3}-\d{4}$ with the test string (555) 123-4567 will highlight the entire string as a match, confirming it follows the expected format.For a more complex example:
- Pattern:
^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$ - Test String:
MyPassword123! - Purpose: Validates strong passwords (minimum 8 characters, at least one uppercase, lowercase, digit, and special character)
Essential Regex Patterns Reference
Character Classes
.- Matches any single character except newline\d- Matches any digit (0-9)\D- Matches any non-digit character\w- Matches word characters (letters, digits, underscore)\W- Matches non-word characters\s- Matches whitespace characters (space, tab, newline)\S- Matches non-whitespace characters
Anchors and Boundaries
^- Matches the start of a string/line$- Matches the end of a string/line\b- Matches word boundaries\B- Matches non-word boundaries
Quantifiers
*- Matches 0 or more occurrences+- Matches 1 or more occurrences?- Matches 0 or 1 occurrence (optional){n}- Matches exactly n occurrences{n,}- Matches n or more occurrences{n,m}- Matches between n and m occurrences
Groups and Alternation
(...)- Creates capturing groups(?:...)- Creates non-capturing groups|- Logical OR operator[...]- Character sets (matches any character within brackets)[^...]- Negated character sets
Common Use Cases
✅ Testing Best Practices
Email Validation
^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$
URL Validation
^https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)$
Credit Card Numbers
^\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}$
IPv4 Address
^(?:(?: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]?)$
⚡ Performance Tip
These patterns provide a solid foundation for building more sophisticated regular expressions tailored to your specific validation requirements.