JavaScript Regex Tester

A regular expression is a compact pattern language for finding and extracting structure in text. It is one of those tools that pays off forever once you spend a few hours learning it. This tester uses the JavaScript regex engine, which is also the engine behind Node.js, modern browsers, and many JSON-handling tools. Type a pattern, choose flags, paste a test string, and see every match highlighted as you type. Capture groups, both numbered and named, appear in the results panel next to each match. The tool also reports common errors like unbalanced parentheses or invalid character classes. Use it to debug a stubborn regex from production logs, build a new pattern incrementally with feedback, or sanity-check that a pattern handles edge cases like empty strings, Unicode characters, and unusual whitespace.