How is a GSTIN structured?

15 characters — a 2-digit state code, the entity's 10-character PAN, a 1-character entity number, the reserved letter Z, and a base-36 check digit computed over the first 14 characters.

How accurate is the validation?

It applies the official GSTN base-36 check-digit algorithm (alternating factors of 1 and 2, summing quotient and remainder modulo 36) and verifies the embedded PAN pattern. A pass means the number is well-formed, not that the registration is active.

Is my GSTIN sent anywhere?

No. The check digit is computed entirely in your browser — privacy-first, the GSTIN never leaves your device and no GST portal lookup is made.

India GSTIN Validator

India GSTIN validator

Validate the format of a 15-character GST Identification Number. The tool decodes the 2-digit state code, checks the embedded 10-character PAN, and recomputes the GSTN base-36 check digit over the first 14 characters: each code point (0–9, A–Z = 0–35) is multiplied by an alternating factor of 1 and 2, and the quotient and remainder of each product divided by 36 are summed; the check value is (36 − sum mod 36) mod 36.

This is privacy-first: the check digit is computed locally with no GST portal lookup. A “valid GSTIN” result means the number is well-formed — verify an active registration on the official GST portal.