Paste a GST number and see whether it is properly formed — including the check digit most tools skip. Nothing is sent anywhere.
A GSTIN is 15 characters, and every part of it means something:
The last character is a mod-36 checksum over the first fourteen. Change one character anywhere in the number and the checksum almost always stops matching — which is how a mistyped GSTIN gets caught at the counter rather than in a return three weeks later. This checker computes it properly. Many free tools only check the length and the pattern, which passes a number that can never exist.
It checks the shape of the number. It cannot tell you whether that GSTIN is registered, active, suspended, or belongs to the business in front of you — there is no public API that answers that, and a tool that implied otherwise would be lying to somebody about to raise a bill. For the registered name and status, look the number up on the GST portal.
What a valid result does tell you is that the number is well formed and free of typos, which is what you need before it goes onto an invoice.
A customer's GSTIN decides whether the bill is B2B, whether it appears in GSTR-1's B2B table, and — through the state code — whether you charge CGST and SGST or IGST. A wrong one puts the invoice in the wrong table and can cost your customer the input credit. Aned Book runs this same check as the number is typed.
No. It verifies the format, the state code, the PAN and the check digit. No public API reports registration status, so nothing here can — use the GST portal for that.
A mod-36 check digit calculated from the first fourteen characters. It is what catches a mistyped number, and this checker computes it rather than assuming it.
No. The check runs entirely in your browser — the same code the billing software uses offline.
The calculator on this page runs the billing engine out of the software itself, not a copy of it — so what it tells you here is what the software would put on the invoice.