Test regular expressions in real time with instant match highlighting
Regular expressions (regex) are powerful pattern-matching tools used across nearly every programming language and text editor. They allow developers to search, validate, extract, and replace text using concise pattern syntax. Whether you're validating email addresses, parsing log files, scraping web content, or building search features, regular expressions provide a flexible and efficient way to work with string data. Our regex tester lets you experiment with patterns in real time, so you can see exactly what your expression matches before deploying it in your code.
Learning regex syntax can feel daunting at first, but mastering a handful of core concepts—literal characters, character classes, quantifiers, anchors, and groups—unlocks an enormous amount of power. Our built-in cheat sheet organizes the most common patterns into collapsible groups, making it easy to look up syntax while you work. Each entry is clickable and inserts directly into the pattern input, so you can build complex expressions piece by piece without memorizing every token.
This regex tester runs entirely in your browser with zero server-side processing. Your test strings and patterns never leave your device, making it safe for sensitive data like passwords, API keys, and personal information. It supports all standard JavaScript regex flags—including global (g), case-insensitive (i), multiline (m), and dotAll (s)—and displays captured groups for each match, making it an essential tool for both learning and day-to-day development.