Regex Tester
Writing Regular Expressions (Regex) can feel like learning an alien language, yet it remains one of the most powerful text-processing tools available for a developer. Our Regex Tester and explainer lets you iterate on complex string patterns in real-time, providing immediate visual matches alongside plain English breakdowns. Simply input your regex and test data to instantly spot boundary issues, validate capturing groups, and ensure your code captures exactly the right text without unexpected side effects.
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Frequently Asked Questions
What flavors of Regex are supported?
This tool utilizes standard JavaScript (ECMAScript) regular expression engine, which handles the most common regex operations.
How do I make my regex case-insensitive?
Append the 'i' flag at the end of your expression, e.g., /pattern/i. The tool will provide UI checkboxes to toggle these flags easily.
What is a capturing group?
A capturing group is created by placing regex tokens within parentheses (). This allows you to extract substrings rather than just confirming a match.
Why did my regex match the whole line instead of a single word?
This is often due to the difference between greedy and lazy matching. Using .* is greedy. You often need .*? to make it lazy.