Verifies the checksum, tells you the state and extracts the PAN. Most online checkers only look at the format — this one computes the real base‑36 check digit, which catches typos.
The GSTIN never leaves your browser — no server, no upload
The 15 characters of a GSTIN follow a fixed structure, and the last character is a base‑36 checksum calculated from the first 14. So if one character is mistyped, the checksum will not match — the mistake is caught before you file.
| Position | What it holds |
|---|---|
| 1–2 | State code |
| 3–12 | PAN |
| 13 | Entity number — which registration this is for that PAN in that state |
| 14 | Always Z |
| 15 | Check digit — calculated from the other 14 |