How to Test Regular Expressions Online Free
Our regex tester provides a powerful environment for testing and debugging regular expressions. Enter your pattern, add test text, configure flags, and see real-time results with match highlighting. Perfect for developers who need to validate regex patterns before implementing them in code.
Advanced Regex Testing Features
Real-time Testing
Test your regular expressions as you type with automatic pattern validation and instant feedback.
Match Visualization
See matches highlighted in your test text with detailed position and capture group information.
Flag Configuration
Full support for all regex flags including global, case-insensitive, multiline, and Unicode modes.
Example Library
Learn from pre-built examples covering email validation, phone numbers, URLs, and advanced patterns.
Common Regex Testing Use Cases
✓ Form Validation
Test patterns for email addresses, phone numbers, postal codes, and other form inputs.
✓ Text Processing
Extract specific data from logs, documents, or structured text files.
✓ Data Cleaning
Find and replace patterns in large datasets or remove unwanted characters.
✓ Code Analysis
Search for specific code patterns, function calls, or variable names in source files.
Why Use Our Regex Tester
Comprehensive Analysis: Get detailed information about matches, capture groups, execution time, and pattern validity with real-time feedback.
Learning Resources: Access built-in examples, quick reference guide, and detailed explanations for all regex flags and patterns.
History Tracking: Automatically save your recent tests for easy reference and pattern reuse across sessions.
Export Results: Download test results, copy patterns to clipboard, and share regex patterns with team members.
Frequently Asked Questions
What regex flavors are supported?
Our regex tester uses JavaScript's built-in RegExp engine, which supports ECMAScript regex syntax. This includes standard features like character classes, quantifiers, anchors, and all modern flags.
How do I test multiline patterns?
Enable the multiline flag (m) to make ^ and $ match line boundaries. For patterns that need to match across lines, use the dotall flag (s) to make . match newline characters.
Can I save my regex patterns?
Yes! Your recent tests are automatically saved to browser history. You can also export results to files or copy patterns to clipboard for use in your projects.
What are capture groups?
Capture groups use parentheses () to extract specific parts of matches. Our tester shows all captured groups with their values and positions for easy debugging.
How do I optimize slow patterns?
Our tester shows execution time for each test. Avoid nested quantifiers, use anchors when possible, and consider non-capturing groups (?:) when you don't need the match data.
Is my data processed securely?
All regex testing happens entirely in your browser - no data is sent to our servers. Your patterns and test strings remain completely private and secure.