Regex Tester

Test regular expressions live with match highlighting and replace preview.

Regex Tester lets you write a regular expression, test it against a string, and see every match highlighted in real time. It supports the global, case-insensitive, and multiline flags, shows a match count, and includes a replace mode so you can preview substitutions before writing them into your code. Developers use it to craft and debug patterns for form validation, log parsing, URL routing, data extraction, and text processing. The live feedback loop eliminates the edit-run-observe cycle that makes regex debugging so tedious in a full IDE — you see the match change the moment you type a character in the pattern. The error display tells you immediately when a pattern is invalid so you do not chase a runtime exception back to a malformed regex. Everything runs in your browser using the JavaScript RegExp engine, which matches the behavior of Node.js, browser JavaScript, and most frontend frameworks.

How Regex Tester works

Regex Tester is a free browser-based utility from Salah Tools Hub. It is designed to give you an immediate result without an account, subscription, or upload to a remote server.

Enter your information into the tool after the page loads, review the result, and use the available copy or download controls. Your input stays on your device while the tool is running.