Regex Tester

Type your pattern into the regex field at the top and type or paste the text you want to test into the test string box. Matches are highlighted in the text instantly as you type, and each match is listed below with its position and any capture groups. Use the flag checkboxes on the right to toggle options like global (find all matches) or case-insensitive matching. Nothing is sent anywhere — it all runs in your browser.

g (global) finds every match instead of just the first. i (ignore case) makes the pattern case-insensitive. m (multiline) makes ^ and $ match the start and end of each line rather than the whole string. s (dotall) lets the dot . also match newline characters. u (unicode) enables full Unicode handling, including \u{…} escapes and surrogate pairs. y (sticky) anchors each match to the position right after the previous one.

Parentheses ( ) create a capture group, and each match in the list shows the text captured by every group, numbered from 1. Named groups written as (?<name>…) are shown by their name too, and you can reference them in the replacement field as $<name>. Use (?:…) when you want to group part of a pattern without capturing it.

Yes. Enter a replacement in the "Replace with" field and the result updates live. You can reference capture groups with $1, $2, …, named groups with $<name>, the whole match with $&, and use $$ for a literal dollar sign. With the global flag on, every match is replaced; without it, only the first. You can copy the replaced text with one click.

It uses your browser's built-in JavaScript (ECMAScript) regular expression engine, so the behavior matches regex in JavaScript and Node.js exactly. Everything runs locally — your pattern and test text never leave your device. Patterns are evaluated in a background worker with a timeout, so even an accidental catastrophic-backtracking pattern won't freeze the page.