Regex Privacy Pattern Tester
Build and test regular expressions for PII detection and privacy scanning. Paste sample text, write or pick a pattern from the built-in library, and see every match highlighted inline. Includes a replacement mode for testing redaction patterns. All computation is pure JavaScript — no data leaves the browser.
$1, $2 for capture groups. Use [REDACTED], ████, or *** for privacy redaction.
Frequently Asked Questions
What is a regular expression used for in privacy?
Regular expressions detect patterns in text — emails, phone numbers, SSNs, credit card numbers — making them essential for auditing documents for inadvertent PII exposure.
Does this tool upload my text?
No. All regex matching runs locally in your browser. Your text never leaves your device.
What built-in patterns are included?
19 pre-built patterns covering emails, UK/US phone numbers, credit cards, SSNs, IBANs, IPv4/IPv6 addresses, AWS keys, PEM private keys, and more.
Can I test my own custom regex?
Yes. Enter any valid JavaScript regular expression and test it against your text with live match highlighting.