Test regular expressions with live matching, color-coded groups, and plain English explanation
🔍Regular ExpressionNo Pattern
📝Test TextNo Text
🎯 Match Results
📖 Pattern Explanation
💡 Sample Patterns
Try these common regex patterns:
About Regex Tester
Our free online regex tester helps developers test and debug regular expressions with real-time matching, color-coded groups, and plain English explanations. Whether you're validating input, parsing text, or learning regex patterns, our tool provides comprehensive testing capabilities.
Features
Live Matching: Real-time regex testing as you type
Color-coded Groups: Visual highlighting of capture groups
Multiple Flags: Support for all regex flags (g, i, m, s, u, y)
Match Details: Detailed information about each match
Pattern Explanation: Plain English explanation of regex patterns
Sample Patterns: Common regex patterns to get started
Copy Results: Easy export of test results
How to Use
Enter your regular expression in the pattern field
Add test text in the text area
Select appropriate regex flags
Click "Test Regex" to see results
Review matches, groups, and explanations
Common Use Cases
✅ Input Validation: Test regex patterns for form validation
✅ Text Parsing: Extract specific patterns from text
✅ Data Cleaning: Find and replace patterns in data
✅ Learning: Understand regex patterns with explanations
✅ Debugging: Troubleshoot complex regex patterns
About this tool
Free Online Regex Tester and Debugger
Test regular expressions in real time. Paste your pattern and test string — matches highlight instantly as you type. Captured groups are shown separately. Toggle flags (global, case-insensitive, multiline, dotall) and see how they change the result. Uses JavaScript's native regex engine; nothing is uploaded.
What is a Regular Expression?
A regular expression (regex) defines a search pattern. Instead of matching a fixed string, it can match an infinite family of strings sharing a common structure. For example, /^\d{4}-\d{2}-\d{2}$/ matches any ISO date like 2026-05-07. Regex is built into every major language and editor.
i — case-insensitive: /hello/i matches "Hello", "HELLO"
m — multiline: ^ and $ match line boundaries
s — dotall: . also matches newlines
What is the difference between .* and .+?
.* matches zero or more characters (can match empty string). .+ requires at least one character. Use .+ when the matched content cannot be empty.
How do I make a quantifier lazy (non-greedy)?
Add ? after it: .*?, .+?. Greedy quantifiers match as much as possible; lazy ones match as little as possible. Example: on <b>text</b>, greedy <.*> matches the whole string; lazy <.*?> matches only <b>.
How do I match a literal dot or other special character?
Escape it with a backslash: \. matches a literal period. Characters needing escaping: . ^ $ * + ? { } [ ] \ | ( )