Quick Answer
How do you test a regular expression?
// Answer
Enter your regex pattern and flags, then paste sample text. The tester highlights every match live and counts them. Flags change behavior: g finds all matches, i is case-insensitive, and m makes ^ and $ match line starts and ends.
Why use this tool
Debug patterns safely
Regex is powerful but easy to get wrong. Testing against real examples with live highlighting helps you see exactly what matches before you ship it. Everything runs locally using the browser\u2019s own regex engine (the same one in your JavaScript).
FAQ
Frequently asked questions
JavaScript (ECMAScript) regular expressions, the same engine used in browsers and Node.js.
g = global (all matches), i = case-insensitive, m = multiline, s = dotall, u = unicode, y = sticky.
The pattern has a syntax error such as an unbalanced bracket or parenthesis. The tool shows the error.
Yes, matching happens entirely in your browser.
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