Text masking

No. Masking runs entirely locally in your browser, without a single server request, and reloading clears everything.

Phone numbers keep the first 3 and last 4 digits (138****5678); ID card numbers keep the 6-digit regional prefix and the last 4 (110101********1234); bank cards (13-19 digits) keep the last 4; e-mails keep the first letter and the full domain (a***@example.com); personal names (two or three Chinese characters sitting right after a phone or ID number, spaces or punctuation allowed between) keep the surname. Rules apply in the order ID card, phone, bank card, e-mail, name, custom - each later rule works on the earlier result, so nothing gets masked twice.

If it does not match a rule's shape, it is left alone - a phone number dialled with an area code, a card number buried inside a longer digit run, or a name in the middle of a long sentence can all miss. The stance is to rather miss a hit than harm a wrong one; for special shapes, express them yourself with the custom regex rule.

Yes. Fill in a JavaScript regex (for instance \d{6}) and the replacement (group back-references like $1 are supported); it applies after the built-in rules. An invalid regex is clearly reported and simply not applied.