Why Regex Tester?
Regex is the most useful tool that nobody can remember. This tester gives you real-time matching with highlights and an explanation of each part of your pattern, so you can write and debug expressions without a separate reference tab.
- Test against realistic sample data, not just "abc123" - patterns behave differently on edge cases.
- Watch the flags: "g" changes whether you see every match or just the first one.
What is Regex Tester?
Regex Tester is a free online tool for testing and debugging regular expressions. Enter your pattern and test string, and see matches highlighted in real-time. The tool provides match groups, flags support, and helpful error messages for invalid patterns.
Common Use Cases
Pattern Development
Build and test complex regex patterns interactively.
Data Validation
Create patterns for validating emails, phones, and other formats.
Text Extraction
Develop patterns for parsing and extracting data from text.
Search and Replace
Test regex patterns before using in code or text editors.
How to Use This Tool
- Enter your regular expression pattern
- Toggle flags (global, case-insensitive, multiline)
- Enter test text to match against
- View highlighted matches and capture groups