Regex tester

JavaScript's (ECMAScript), as used in browsers and Node.js, run by this browser. They support lookahead and lookbehind, named groups and Unicode property escapes such as \p{L} (with the u or v flag), but not features from other engines such as possessive quantifiers, atomic groups or recursion.

g (global: every match), i (ignore case), m (multiline: ^ and $ at line breaks), s (dotAll: . matches line breaks), u (unicode), v (unicode sets), y (sticky: only at the start (with g, each match right after the last)), d (group indices (always on here)). Without g only the first match is found.

Some patterns take exponentially long on text they almost match, for example (a+)+$ on a long run of a's followed by b: the engine tries every way to split the a's (catastrophic backtracking). Matching runs separately from the page and is stopped after 1 second, so the tab stays usable; making nested repeats more specific fixes it.

$1, $2 … insert numbered groups, $<name> a named group, $& the whole match and $$ a dollar sign. With the dates example, $<day>/$<month>/$<year> turns "Released 2026-09-30, patched 2026-10-02." into "Released 30/09/2026, patched 02/10/2026.".

No. The pattern and the text are matched in this tab. They aren't sent to our servers, and they aren't kept after you leave the page.