GSTIN Validator
Checks a GSTIN's format AND its check-digit checksum — catching typos a plain regex would miss — then decodes the state, PAN and entity type it encodes.
Enter a 15-character GSTIN to check its format, checksum, and what it tells you about the business.
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Start free for 3 monthsFrequently asked questions
What is a GSTIN?
A GSTIN (GST Identification Number) is the 15-character registration number every GST-registered business in India gets. It's structured as: 2-digit state code + 10-character PAN + 1-digit entity/registration count + a fixed 'Z' + 1 check-digit character.
How is a GSTIN checksum calculated?
The 15th character is a check digit computed from the first 14 characters using a base-36 algorithm (digits 0-9 and letters A-Z), similar to the check digit on a PAN. This tool computes the expected check digit and compares it to the one you entered — a mismatch usually means a typo or a transposed character somewhere in the GSTIN.
Why doesn't a plain format check catch every mistake?
A regex only confirms the GSTIN has the right SHAPE (right number of digits and letters in the right positions) — it will happily accept a string with a single wrong or swapped digit as long as the pattern still fits. The checksum step catches those, because a random typo almost never produces a matching check digit by coincidence.
Does a valid GSTIN here mean the registration is active?
No. This tool only confirms the GSTIN is correctly FORMED (valid format and checksum) — the same check BillForge does before saving a client's GSTIN on an invoice. It does not call the GST portal, so it can't tell you whether that registration is currently active, cancelled, or suspended. For that, use the official GST portal's taxpayer search.
Is this GSTIN validator free?
Yes, completely free with no login. It runs the exact same validateGstinFull() check BillForge uses internally when you add a client's GSTIN to an invoice.