Regex Tester

Free Regex Tester – Test Regular Expressions Online

Introduction

Need to test regular expressions? Our Regex Tester Tool helps you test, debug, and validate regex patterns instantly. Perfect for developers, data analysts, and anyone working with pattern matching.

This free tool provides real-time regex testing with syntax highlighting and error detection.

Common Use Cases

Regex testing for every need:

Data Validation

• Email validation
• Phone number formats
• URL validation
• Password strength

Text Processing

• Extract specific patterns
• Find and replace
• Data cleaning
• Log file parsing

Web Development

• Form validation
• Input sanitization
• Route matching
• API parameter validation

Data Analysis

• Extract data from text
• Parse CSV/JSON
• Clean datasets
• Pattern discovery

How to Use the Tool

Testing regex is simple:

Step 1: Enter regex pattern
Step 2: Add flags (g, m, i) if needed
Step 3: Paste test string
Step 4: View highlighted matches
Step 5: Refine pattern as needed

Regex Basics

Understanding regex syntax:

Literal Characters

abc matches "abc" exactly

Character Classes

[abc] matches a, b, or c
[0-9] matches any digit
[a-z] matches any lowercase letter

Metacharacters

. matches any character
\d matches digit (0-9)
\w matches word character (a-z, A-Z, 0-9, _)
\s matches whitespace

Quantifiers

* matches 0 or more
+ matches 1 or more
? matches 0 or 1
{n} matches exactly n times
{n,m} matches n to m times

Regex Flags

Modify pattern behavior:

g (Global)

Find all matches, not just first one.

i (Case Insensitive)

Ignore case when matching.

m (Multiline)

^ and $ match line starts/ends, not just string.

s (Dotall)

. matches newlines too.

Common Patterns

Frequently used regex:

Email Validation

^[^\s@]+@[^\s@]+\.[^\s@]+$

URL Matching

^(https?|ftp)://[^\s/$.?#].[^\s]*$

Phone Numbers

^\+?[\d\s()-]{10,}$

Dates (YYYY-MM-DD)

^\d{4}-\d{2}-\d{2}$

IP Address

^(\d{1,3}\.){3}\d{1,3}$

Best Practices

Effective regex usage:

Keep It Simple

Complex regex is hard to maintain and debug.

Test Thoroughly

Test edge cases and invalid inputs.

Use Comments

Document complex patterns for future reference.

Escape Special Characters

Use backslash to escape: \. \* \+

Common Mistakes to Avoid

Don't fall into these traps:

Forgetting to Escape

Problem: . matches any character
Solution: Use \. for literal dot

Greedy Matching

Problem: .* matches too much
Solution: Use .*? for non-greedy

Not Testing Edge Cases

Problem: Pattern fails on real data
Solution: Test with various inputs

Privacy and Security

Your data is completely safe:

• No Data Storage: We never save patterns or test strings
• Client-Side Processing: All testing in your browser
• No Account Required: Use anonymously

Conclusion

Regular expressions are powerful tools for pattern matching and validation. Whether you're validating forms, parsing data, or cleaning text, our free regex tester helps you create and test patterns instantly.

No downloads, no registration, and complete privacy. Start testing regex today!