Regex Tester.

A regex tester lets you write a regular expression and immediately see what it matches inside sample text. Type a pattern in the top field, paste the text you want to search below it, flip the flags you need — g for all matches, i for case-insensitive, m for multiline anchors, s to let . cross newlines, u for full Unicode — and matches highlight in place as you type. Toggle the Replace panel to preview substitutions before pasting the regex back into your code.

Reach for this tool when a pattern in your code isn’t behaving and you want to isolate it from the surrounding logic. It’s the fastest way to confirm that ^https?:// matches both http and https URLs, that your email regex tolerates plus-signs, or that a backreference is doing what you think it is. The pattern runs through your browser’s native RegExp engine — the same engine your Node, Bun, or Chrome runtime uses — so what you see here is what you’ll get in production.