Regex Tester
Test regular expressions live - matches highlighted, groups shown, errors caught.
Flags:
Match Preview
About this tool
Regular expressions (regex) are patterns used for matching, searching, and replacing text. Flags modify matching behavior: g finds all matches (not just the first), i ignores letter case, m makes ^ and $ match the start/end of each line (not just the whole string), and s makes . match newline characters as well. Parentheses () create capture groups that extract sub-matches. This tester runs entirely in your browser with JavaScript's native RegExp engine.