About this tool
Write a pattern and see every match highlighted in your test string as you type, with capture groups, named groups and match positions listed underneath. Toggle the global, ignore-case, multiline, dotall, unicode and sticky flags individually.
Matching runs in a Web Worker with a hard timeout, so a catastrophically backtracking pattern such as (a+)+$ stops cleanly instead of freezing the page — a common failure in browser-based regex testers.