Use cases · for developers at fintech, lending and B2B SaaS companies
GSTIN verification API: free format and checksum check
Last updated 2 November 2026 · by Venu Gopal Reddy Muvva, founder
IndianFirmData checks a GSTIN for free from its API or MCP server: GET /api/v1/identifiers/decode?value=<GSTIN> returns whether the format and check digit are valid, the state, the PAN inside it, the holder type, and the matching company when it is in our index. That catches typing mistakes and made-up numbers at 0 credits. It does not yet say whether the registration is active, because live GST status needs a licensed GST Suvidha Provider; for that today, use a vendor such as Surepass, whose GST verification API detects inactive GSTINs.
Steps in IndianFirmData
1. Get an API key
Sign up free, with no card, and create a key in Dashboard → API keys.
2. Send the GSTIN
GET /api/v1/identifiers/decode?value=<GSTIN> with Authorization: Bearer <key>. Lower case is fine. The call costs 0 credits, during the free period and after it.
3. Read the result
You get type gstin, valid true or false, and the decoded parts: state code and state, the embedded PAN, the PAN holder type (company, firm, individual and so on), the registration number in the state and whether the checksum is right.
4. Check many at once
Call the endpoint once per GSTIN from your own code, or let an AI agent call decode_identifier through the MCP server. Each check is free.
What an offline check proves, and what it does not
The 15th character of a GSTIN is calculated from the first 14, so a wrong or invented number almost always fails the check. A pass tells you the number is well formed, belongs to a real state code and contains a well-formed PAN. It does not tell you the registration is active, who holds it or whether returns are filed; that needs the GST network.
We never automate the GST portal: its search is behind a CAPTCHA. Our live status lookup (GET /api/v1/identifiers/gst-status) is built for a licensed GSP and returns 501 until we sign one.
Why check it here
The same call checks CIN, PAN, Udyam, LEI and ISIN numbers, so one free endpoint validates every ID a business gives you at sign-up. When the company is in our index, you also get its sourced record, and the MCP server lets an AI agent run the same checks.
GSTIN verification APIs compared: IndianFirmData, Signzy, Surepass and Zoop
| What | IndianFirmData | Signzy | Surepass | Zoop |
|---|---|---|---|---|
| What it is | Indian company data API, MCP server and dashboard | Global identity verification and compliance platform | Digital identity verification platform for Indian financial services | Verification of individuals and businesses in India |
| Public price | Yes: free for 3 months, then about ₹1.5 per 1,000 credits at cost (est.) | Not listed publicly | Not listed publicly | Not listed publicly |
| Start | Self-serve sign-up, no card | Book a demo | Free account form; the team contacts you | Book a demo |
| GSTIN check | Free offline check: format, check digit, state, PAN inside, holder type | "Aadhar & GST Checks" listed for India | GST verification API, also with OTP; bulk | Lists a GST verification API |
| Live GST active / inactive status | Not available yet (needs a licensed GSP) | Not stated | Yes: detects fake and inactive GSTINs | Not stated |
| PAN to GSTIN | No (PAN is read out of a GSTIN, not the reverse) | Not stated | Yes (PAN to GST API) | Not stated |
| Source, licence and freshness per field | Yes, every field | Not stated | Not stated | Not stated |
| MCP server for AI agents | Yes, 16 tools | Not mentioned | Not mentioned | Not mentioned |
Competitor facts are from their own public websites, checked 2 Nov 2026: signzy.com (home, India API marketplace, KYB and database-check pages; /pricing returned 404), surepass.io (home, business-verification, mca-data-apis-cin-din, gst-verification-api, get-api-key; /pricing shows no prices) and zoop.one (home, plug-and-play APIs, sitemap; /pricing returned 404). "Not stated" means we did not find it on those pages, not that the product cannot do it. Signzy, Surepass and Zoop are trademarks of their owners. IndianFirmData is not affiliated with, endorsed by or sponsored by any of them. Tell us if anything is out of date: [email protected].
When IndianFirmData is not the right tool
If you must confirm today that a GST registration is active, or find the GSTINs behind a PAN, pick a vendor with live GST data: Surepass lists GST verification (fake and inactive GSTINs, bulk) and PAN to GST APIs. IndianFirmData's live GST status is not switched on until we sign a licensed GSP.
Questions
Is the GSTIN verification API free?
The offline check is free for ever: 0 credits per call. Live GST status, when it arrives, will be passed through at the GSP's fee with no markup.
Does a valid checksum mean the GSTIN is active?
No. It means the number is well formed. Whether the registration is active needs the GST network, through a licensed GSP.
Can my AI agent verify GSTINs?
Yes. The MCP server's decode_identifier tool runs the same free check, so Claude, Cursor or any MCP client can validate a GSTIN and read the PAN and state inside it.
Do you scrape the GST portal?
No. Its search is behind a CAPTCHA and we never automate it.
Try it on a company you know.
Start free — 3 months on usRelated: CIN lookup API · Verify a GSTIN number · Check a company is real · IndianFirmData vs Surepass · IndianFirmData vs Signzy · IndianFirmData vs Zoop · Pricing