Test regular expressions with live match highlighting.
The Regex Tester lets you write, test, and debug regular expressions against real sample text in real time, with each match highlighted as you type. Whether you are extracting emails from a log file, validating form inputs, or learning regex syntax for the first time, this interactive tester gives you instant visual feedback without needing a code editor.
The tester uses JavaScript's built-in RegExp engine, which closely matches the behaviour you will get in browsers and Node.js. For server-side work in Python, PHP, or Go you may encounter minor differences around lookbehinds, Unicode properties, or named groups, but the core syntax is the same.
Enable the Multiline (m) flag so that ^ and $ match the start and end of each line rather than the whole string. If you also want the dot (.) to match newline characters, enable the Dotall (s) flag at the same time.
Without the global flag, the regex engine stops after finding the first match. Adding the g flag makes it find all non-overlapping matches in the input, which is what you usually want when extracting multiple values.
Yes. JavaScript supports named capture groups with the syntax (?<name>...). The tester displays each named group alongside its matched value, which makes complex patterns far easier to read and debug.