GSTIN Validator
Paste any 15-character GSTIN and instantly verify the format, the Mod-36 checksum, the state, the embedded PAN, and the type of registered entity. Everything runs in your browser — no signup, no API call, no logging.
How to use this GSTIN validator
Paste or type a 15-character GSTIN into the box. The tool normalises the case and checks two things in real time. First, the structural shape — state code (digits), PAN (5 letters · 4 digits · 1 letter), entity / branch code, the fixed letter Z, and the final checksum. Second, the Mod-36 algorithm: each of the first 14 characters is multiplied by an alternating factor of 1 / 2 (from right), the products are digit-summed, and the remainder modulo 36 yields the expected check character.
If both checks pass, you get a structural verdict plus a breakdown: the state name from the first 2 digits, the embedded PAN, and the holder type from the 4th character of the PAN (P = Individual, C = Company, F = Firm or LLP, H = HUF, T = Trust, and so on). A pass here does not confirm the GSTIN is active on the GST portal — for that you need a live portal lookup, which HelloBooks performs automatically when you add a customer or vendor.
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Frequently asked questions
- What is a GSTIN and what do the 15 characters mean?
- A GSTIN (Goods and Services Tax Identification Number) is a 15-character alphanumeric identifier issued by the Indian GST authority. The first 2 digits are the state code, the next 10 are the registrant's PAN, the 13th is the entity / branch number (1–9 then A–Z), the 14th is a fixed letter Z, and the 15th is a Mod-36 checksum that detects typos. The 4th character of the embedded PAN tells you whether the holder is an individual (P), company (C), firm / LLP (F), HUF (H), trust (T), AOP (A), BOI (B), government (G), local authority (L), or artificial juridical person (J).
- How does this GSTIN validator work?
- It checks two things, fully in your browser, with no API call. First, the shape: positions 1–2 must be digits, 3–7 letters, 8–11 digits, 12 a letter, 13 a digit or letter, 14 the letter Z. Second, the Mod-36 checksum: each of the first 14 characters has a value 0–35 (digits 0–9, then A=10 … Z=35), and the standard Mod-36 algorithm produces a check character that must match position 15. If both pass, the GSTIN is structurally valid.
- Does "structurally valid" mean the GSTIN is active and genuine?
- No. A structural pass only tells you the number is well-formed and not a typo. It does not confirm the GSTIN is registered, active, suspended, or cancelled on the GST portal. For status confirmation you must call the GST portal's search API or use software (like HelloBooks) that pings it for you when you add a vendor or customer.
- Why might a real GSTIN fail the checksum?
- Almost always, the GSTIN has been typed or copy-pasted incorrectly — a 0 mistaken for an O, a 1 for an I, characters dropped or swapped. If you got the GSTIN from a tax invoice, ask the supplier to re-share it. If the checksum still fails after a careful re-check, the GSTIN is not a genuine one; do not claim input tax credit against it.