RegEx Tester
Test and validate regular expressions with real-time matching
Regular Expression
Test String
About RegEx Tester
A regular expression (regex) is a sequence of characters that define a search pattern. Use this tool to test and validate your regex patterns in real-time.
Features:
- Real-time regex matching as you type
- Visual highlighting of matches in the test string
- Detailed match information including position and capture groups
- Pattern explanation to understand regex components
- Support for all standard regex flags (g, i, m, s, u, y)
- Instant validation with clear error messages
Note: All processing happens in your browser. Your data never leaves your device.
What are Regular Expressions?
Regular expressions (regex or regexp) are powerful patterns used to match, search, and manipulate text. They provide a concise and flexible way to identify strings of text, such as particular characters, words, or patterns of characters. Regular expressions are supported in virtually all modern programming languages and text editors.
Think of regex as a mini-language for describing text patterns. Instead of searching for exact text, you can search for patterns like "any email address," "any phone number," or "any word starting with a capital letter."
Common Use Cases
Regular expressions are used in countless scenarios across software development and data processing:
Validation
- • Email addresses
- • Phone numbers
- • Credit card numbers
- • URLs and domains
- • Passwords strength
Data Extraction
- • Parsing log files
- • Web scraping
- • Extracting data from text
- • Finding specific patterns
- • Code analysis
Text Processing
- • Search and replace
- • Text formatting
- • Removing whitespace
- • String manipulation
- • Data cleaning
Development
- • Input validation
- • Form handling
- • API data parsing
- • Configuration files
- • Syntax highlighting
How to Use This Tool Effectively
Step-by-Step Guide:
Enter Your Pattern
Type your regular expression in the "Pattern" field. Start simple and gradually add complexity. For example, start with \d to match digits.
Select Flags
Choose appropriate flags for your use case. Use "g" for global matching (find all matches), "i" for case-insensitive matching, or combine multiple flags as needed.
Add Test String
Paste or type the text you want to test against your pattern. The tool will automatically highlight matches and show detailed information about each match found.
Analyze Results
Review the highlighted matches, check the explanation panel to understand your pattern, and examine the match information panel for details about positions and capture groups.
Common Regex Examples:
^[\w-\.]+@([\w-]+\.)+[\w-]4$→ Match email addresses\d3-\d3-\d4→ Match phone numbers (format: 123-456-7890)https?://[^\s]+→ Match URLs starting with http or https^(?=.*[A-Z])(?=.*[a-z])(?=.*\d).{8,}$→ Strong password (uppercase, lowercase, digit, 8+ chars)#[0-9A-Fa-f]6→ Match hex color codes (e.g., #FF5733)Pro Tips
- • Start with simple patterns and build complexity gradually
- • Test your regex with multiple examples to ensure it works as expected
- • Use non-capturing groups
(?:...)when you don't need to extract the match - • Be careful with greedy quantifiers - add
?for non-greedy matching - • Remember to escape special characters with a backslash when you want to match them literally