Test regular expressions against sample text with live match highlighting.
JavaScript's native RegExp engine (ECMAScript regex) — the same syntax used in browsers and Node.js. Most patterns are compatible with PCRE, but some advanced features (like recursive patterns) differ.
Check your flags — forgetting the g flag means only the first match is found and highlighted, and forgetting i means the match is case-sensitive.
Yes — enable the "m" flag so ^ and $ match the start/end of each line rather than only the start/end of the whole string.
Check for a missing anchor (^ or $) or an overly greedy quantifier (.* instead of .*?) — both are common causes of over-matching.