How regex tester works
Runs JavaScript regular expressions in an isolated Web Worker with a 300 ms execution limit.
Try an example
Pattern \d+ against item42 → 42.
Good to know
Potentially expensive expressions are terminated. Max 100,000 text characters, 1,000 pattern characters and 1,000 matches. Flags follow JavaScript regex semantics.
Your privacy
Processing happens on this device. We do not upload your input, put it in share links or save it to your favourites. Closing this tab discards the working input; downloaded results remain wherever you save them.