What is a GST API?

A GST API is an interface that lets software exchange GST data with the GST system over HTTP, instead of a person doing it in a browser. The most common kind is a GSTIN verification API: your application sends a GST number and gets back the registered business’s name, status, addresses and return filing history as structured JSON, in a single request.

Start free — 20 credits included Read the API docs

"GST API" covers four quite different things

People searching for a GST API are often looking for one of four unrelated capabilities. They differ in what they touch, who has to consent, and how they are priced — so it is worth being precise about which one you actually need.

This is what GSTIN API does

Taxpayer / GSTIN verification

Read-only, public data

Looks up a GST registration by GSTIN and returns legal name, trade name, status, addresses, jurisdiction, return filing history and e-invoicing enablement. No consent from the taxpayer is needed, because registration details are published.

Return filing

Write access to a taxpayer’s own account

Pushes GSTR-1, GSTR-3B and related returns into the GST system on behalf of a taxpayer. Reached through a GST Suvidha Provider, and requires the taxpayer to authenticate and grant access — you cannot file for someone without it.

E-invoicing / IRP

Write access, per-invoice

Registers a B2B invoice with the Invoice Registration Portal and returns an IRN and signed QR code. Used inside billing software for taxpayers above the e-invoicing turnover threshold.

E-way bill

Write access, per-consignment

Generates, updates, extends and cancels e-way bills for goods in transit through the e-way bill system. Typically integrated by logistics and dispatch software.

What a call actually looks like

Authentication is a single header. There is no OAuth dance, no token exchange and no SDK to install — your API key goes in x-api-key and the GSTIN goes in the path.

Request

 curl https://gstinapi.com/api/get-taxpayer-info/27AAACR5055K1Z7 \
  -H "x-api-key: YOUR_API_KEY"

Response (abridged)

{
  "taxpayer_data": {
    "gstin": "27AAACR5055K1Z7",
    "name": "REGISTERED LEGAL NAME",
    "tradename": "Trade Name",
    "status": "Active",
    "registrationDate": "2017-07-01",
    "constitution": "Public Limited Company",
    "pradr": { "addr": { "st": "...", "loc": "...", "stcd": "Maharashtra", "pncd": "400001" } },
    "einvoiceStatus": "Yes"
  },
  "filing_data": [
    { "rtntype": "GSTR3B", "taxp": "July", "fy": "2026-27", "dof": "2026-08-18" },
    { "rtntype": "GSTR1",  "taxp": "July", "fy": "2026-27", "dof": "2026-08-11" }
  ]
}

Every field, plus code in JavaScript, PHP and Python, is in the API documentation. For a full walkthrough from key to first parsed response, see how to verify a GST number using an API.

Who uses a GST API, and why

The common thread is a check that has to happen inside software, at a moment when nobody is available to open a browser — at signup, at invoice entry, or in a nightly job over a vendor master.

Marketplaces and platforms

Verify a seller’s GSTIN at signup so a fake or cancelled registration never reaches the catalogue.

Accounts payable teams

Re-check a vendor master before a payment run, instead of discovering a cancelled GSTIN when input tax credit is denied.

Lenders and NBFCs

Use registration status and filing regularity as a business-KYC and cash-flow signal alongside PAN and bank checks.

ERP and accounting software

Validate a GSTIN at the point a customer or supplier record is created, so bad data never enters the ledger.

The alternative — scripting the GST portal itself — breaks on the captcha, the session timeout and the next markup change, and is against the portal’s terms. We compared the two approaches honestly in GST API vs scraping the GST portal.

What a GST API costs, and how to start

Verification APIs are priced per call; filing and e-invoicing APIs are usually GSP subscriptions with a monthly commitment, which is a materially different cost profile. Here, verification is pay-as-you-go: 20 free credits on email verification, then ₹0.50 per verification, dropping to ₹0.40 once you cross 2,500 credits. No subscription, no minimum spend, no expiry pressure — the pricing page has the full breakdown.

1

Create an account and verify your email

Sign up at gstinapi.com. Verifying your email credits the account with 20 free verifications, enough to test against real GSTINs.
2

Generate an API key

Create a key from the dashboard. It is sent in the x-api-key header on every request and can be rotated at any time.
3

Call the endpoint

Send GET https://gstinapi.com/api/get-taxpayer-info/{gstin} with your key in the header. One successful lookup consumes one credit; a GSTIN that does not exist is a real answer and is not billed.
4

Parse the response

Read taxpayer_data.status first, then match taxpayer_data.name and the principal address against your own record. filing_data carries the recent GSTR-1 and GSTR-3B history.
5

Handle failures explicitly

Code for 401 on a bad key, 402 when credits run out, and 502 when the upstream government system is unavailable — the last of these is transient and worth retrying with backoff.

Further reading: what a GSTIN verification API is, the longer GST verification API guide, and the developer overview with per-language integration guides.

GST API — common questions

A GST API is an interface that lets software exchange GST data with the GST system over HTTP instead of a person doing it in a browser. The most common kind is a GSTIN verification API: your application sends a GST number and receives the registered business’s name, status, addresses and return filing history back as structured JSON, in one request.

API stands for Application Programming Interface — a defined way for one program to ask another program for something. In a GST context it means your billing, ERP or onboarding software can query or submit GST data directly, rather than a person logging into gst.gov.in and copying fields across by hand.

Four broad kinds: taxpayer or GSTIN verification APIs (read-only lookups of published registration data), return filing APIs (submit GSTR-1 and GSTR-3B for a taxpayer, via a GST Suvidha Provider), e-invoicing APIs (register a B2B invoice with the Invoice Registration Portal and receive an IRN), and e-way bill APIs (generate and manage e-way bills). They differ in access model, authentication and cost.

No. GSP authorisation matters for APIs that write into a taxpayer’s GST account — return filing, and e-invoicing routed through the GST system. Verification APIs read published registration data, so any developer can sign up and start calling one immediately.

For verification, no — GST registration details are published by the government precisely so that counterparties can check them, with no OTP or consent step. For filing and e-invoicing APIs, yes: those act on a taxpayer’s behalf and require that taxpayer to authenticate and authorise access.

Verification APIs are usually priced per call. GSTIN API gives 20 free credits when you verify your email, then charges ₹0.50 per verification, dropping to ₹0.40 past 2,500 credits, with no subscription or minimum spend. Filing and e-invoicing APIs are typically sold as GSP subscriptions with monthly commitments, which is a different order of cost.

The portal is designed for a person: it puts a captcha in front of every search and expires sessions. Automating it is fragile, breaks whenever the page changes, and is against the portal’s terms. An API returns a stable JSON contract you can depend on, with no captcha and no HTML parsing.

An account, an API key, and any HTTP client. There is no SDK to install — a single GET request with your key in the x-api-key header returns the full taxpayer record as JSON, and the 20 free credits are enough to test it against real GSTINs before you spend anything.

Make your first GST API call

One endpoint, one header, predictable JSON. Sign up, generate a key, and verify a real GSTIN with the 20 free credits.

Get an API key free Explore the GST API