Regex Tester
Build, test, and debug regular expressions with our interactive regex tester. See matches highlighted in real-time, use preset patterns, and learn regex with our quick reference guide.
What is Regex Tester?
Regular expressions (regex) are powerful patterns used to match character combinations in strings. Our Regex Tester helps you build and test regex patterns with instant visual feedback, making it easier to validate data, extract information, and manipulate text in your applications.
Test & Debug
Test patterns against sample text with instant results
Preset Patterns
Use common patterns for emails, URLs, phones, and more
Quick Reference
Built-in syntax guide for learning regex
Match email addresses
Phone
Match US phone numbers
URL
Match HTTP/HTTPS URLs
Date (MM/DD/YYYY)
Match dates in MM/DD/YYYY format
IP Address
Match IPv4 addresses
ZIP Code
Match US ZIP codes
Presets
Regular Expression
Test String
Results
No matches found.
How to Use Regex Tester
Choose or Enter Pattern
Select a preset pattern or enter your own regex in the pattern field.
Set Flags
Add flags like g (global), i (case-insensitive), or m (multiline) as needed.
Enter Test Text
Paste or type the text you want to test against your regex pattern.
Test & Copy
Click Test to see matches highlighted, then copy your pattern for use.
Common Use Cases
- ✓Form Validation: Validate email addresses, phone numbers, passwords, and other user input in web forms.
- ✓Data Extraction: Extract specific information from logs, documents, or web pages (emails, URLs, dates).
- ✓Search & Replace: Find and replace text patterns in code editors, IDEs, or command-line tools.
- ✓Data Parsing: Parse structured data like CSV, JSON, or custom formats with complex patterns.
- ✓URL Routing: Define URL patterns for web application routing and API endpoints.
Regex Flags Guide
g - Global
Find all matches in the string, not just the first one
i - Case-insensitive
Match letters regardless of case (A = a)
m - Multiline
^ and $ match start/end of each line, not just string
s - Dotall
Dot (.) matches newlines as well as other characters
Frequently Asked Questions
What are regular expressions used for?
Regular expressions are used for pattern matching in text. Common uses include validating user input (emails, phone numbers), searching and replacing text, extracting data from documents, and parsing structured data formats.
Why is my regex not working?
Common issues include: forgetting to escape special characters (use \ before . * + ? ^ $ etc.), incorrect flags (check if you need case-insensitive matching), or syntax errors. The error message will help identify the problem.
What does the 'g' flag do?
The 'g' (global) flag tells the regex engine to find all matches in the text, not just stop at the first match. Without it, you'll only get the first occurrence.
How do I match special characters literally?
Escape special characters with a backslash (\). Special characters include: . * + ? ^ $ ( ) [ ] | \ / To match a literal dot, use \. instead of just .
Are these patterns safe to use in production?
The preset patterns are good starting points but may need customization for your specific requirements. Always test thoroughly with your actual data. Some patterns (like email) have complex standards that simple regex may not fully cover.
Regex Quick Reference
Characters
.- Any character except newline\d- Digit (0-9)\D- Non-digit\w- Word character (a-z, A-Z, 0-9, _)\W- Non-word character\s- Whitespace\S- Non-whitespace
Quantifiers
*- 0 or more+- 1 or more?- 0 or 1{n}- Exactly n{n,}- At least n{n,m}- Between n and m
Anchors
^- Start of string$- End of string\b- Word boundary\B- Non-word boundary
Groups & Alternation
(...)- Capturing group(?:...)- Non-capturing group|- Alternation (OR)[...]- Character class[^...]- Negated character class
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