Test a regular expression

Test JavaScript regular expressions against representative text without uploading source data. Enter a pattern separately from its flags, then inspect matched values, source indexes, and capture groups. Global patterns return up to the first 1,000 matches; non-global patterns return the first match, mirroring JavaScript behavior.

Regular expressions can suffer catastrophic backtracking. FileGizmo runs every test in a disposable browser worker and terminates it after 750 milliseconds, preventing a pathological pattern from permanently freezing the interface. The timeout is a safety boundary, not proof that a pattern is efficient against every production input.

Syntax follows the current browser’s JavaScript RegExp implementation, including supported Unicode features and flags. Patterns and test content remain local and are not saved. Validate important expressions with diverse realistic cases, edge conditions, and performance tests before using them for security checks, routing, validation, or processing untrusted large inputs.