Validates a Chinese second-generation resident identity card number (18 digits, the last one possibly the letter X). The check digit is verified with the national standard GB 11643 / ISO 7064 MOD 11-2 algorithm: each of the first 17 digits is multiplied by a fixed weight, the weighted sum is taken modulo 11, and the result maps to the expected 18th character. If it matches, the tool decodes the embedded fields: the birth date from digits 7–14, gender from the 17th digit (odd = male, even = female) and the current age computed from the birth date.
This tool only checks the checksum and reads the birth date and gender — it does not look up the region of the address code and does not verify that a number was actually issued. Everything runs locally in your browser and nothing is ever uploaded, so the ID number never leaves your device.