Type a pattern (JavaScript flavor) and flags, and watch matches highlight live in your test text — every match numbered, with its capture groups and positions in a table. A replace field previews $1/$ substitutions. Runaway patterns are stopped after 2 seconds.
Privacy ledger
Data acquired
None.
Libraries used
Lit 3 — bundled into the tool file itself.
Data stored
None.
Data transmitted
None.
Use it on your own page
Download the tool as a single self-contained HTML file: readable source with the Lit library included, zero network requests — it works opened straight from your disk, and you can customize everything.