Regex Tester & Validator

Matches lines containing either exactly 12 digits or a 34-digit string consisting of a 22-digit prefix followed by a 12-digit suffix, capturing the final 12 digits in group 1. It is useful for parsing shipping or courier tracking numbers where an optional 22-digit routing/header portion (e.g., from a longer barcode) precedes the core 12-digit identifier. With the global and multiline flags, it can validate and extract these values across multiple lines at once.