Regex Tester
Test a pattern against sample text with live match highlighting, capture groups, and a replace preview. Runs entirely in your browser.
//g
Runs natively in your browser — nothing you paste leaves this page. A pathological pattern can still hang this tab (catastrophic backtracking / ReDoS); input is capped to 50,000 chars and 5,000 matches to bound it, but a hard timeout would need a Web Worker.