Regex Replace Tester

Enter a pattern, flags, replacement string, and source text to preview first-match or global replacement without blocking the main UI.

Pattern

Flags

Replacement

Replace all matches by adding g

Source text

Replacement result

ReadyUses native JavaScript replacement-string semantics such as $&, $1, and named-group substitutions.

How to use this Regex Replace Tester

Test JavaScript regular-expression replacements safely in a browser worker. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.