The request every tool sends
A GET to https://www.gstinapi.in/v1/gstin/ followed by the GSTIN, with your key in an x-api-key header. That is the whole integration. The response carries success, and a data object with the legal name, trade name, status, taxpayer type, registration date and address.
GET https://www.gstinapi.in/v1/gstin/24APLPV0398G1ZH
x-api-key: gak_your_api_keyThe test GSTIN 00AAAAA0000A1ZT returns a fixed, real-shaped response and never spends a credit — use it while you build the workflow.
n8n: the HTTP Request node
Add an HTTP Request node after whatever supplies the GSTIN. Set the method to GET and the URL to the expression below, which reads a field called gstin from the previous node. Under Authentication choose Generic Credential Type, then Header Auth. Create a credential whose name is x-api-key and whose value is your key.
https://www.gstinapi.in/v1/gstin/{{ $json.gstin }}The URL field, as an n8n expression.
Later nodes can read the result with expressions such as {{ $json.data.status }} and {{ $json.data.legal_name }}. Add an IF node on {{ $json.success }} to route verified and not-verified vendors differently.
Retries: open the node Settings and switch on Retry On Fail, with a Wait Between Tries of 2000 ms. It retries any failure, including a 404 for a GSTIN that does not exist. That is harmless, since a 404 is never charged, but it slows the run. If that matters, turn on the Never Error response option and branch on success in an IF node instead.
Rate limit: each key allows 60 requests a minute. When a workflow feeds many GSTINs through the node, open Options, then Batching, and set Items per Batch to 1 and Batch Interval to 1000 ms, which sends one request a second.
Sources: n8n docs: HTTP Request node · n8n docs: handling API rate limits · n8n docs: error handling
Zapier: Webhooks by Zapier
Add an action step, choose the Webhooks by Zapier app, and pick the GET event. Webhooks by Zapier is a Premium app, so it needs a paid Zapier plan.
Put https://www.gstinapi.in/v1/gstin/ in the URL field and, straight after it, insert the GSTIN field from the earlier step. In the Headers field add x-api-key with your key as the value. Test the step: the response fields, including the legal name and status, become available to map into the steps that follow.
A 404 means the GST network has no such registration, a 400 means the GSTIN is malformed, and both are never charged. A 429 means you sent more than 60 requests a minute, and a 502 is a temporary upstream error that is safe to retry.
Sources: Zapier: Webhooks by Zapier actions
Frequently asked questions
Do I need to write code to verify a GSTIN in n8n or Zapier?
No. Both tools have a generic HTTP step. You give it a URL, an x-api-key header and the GSTIN from the previous step, and the response fields become available to the steps after it.
Is there a gstinapi.in app in the n8n or Zapier directory?
No. There is no dedicated connector, and none is needed: the API is a single GET request, which the HTTP Request node and Webhooks by Zapier both send.
What does a workflow run cost?
One credit per successful lookup. Malformed GSTINs, unregistered numbers and provider errors are not charged. Every account starts with up to 100 free lookups, and credits never expire.
How do I avoid spending credits while I build the workflow?
Use the test GSTIN 00AAAAA0000A1ZT. It returns a fixed, real-shaped response and never consumes a credit.
Can a workflow watch a vendor for changes instead of checking on every run?
Yes. Put the vendors on a monitoring watchlist and register a webhook: the changes are POSTed to your workflow, which starts from an n8n Webhook trigger or a Zapier Catch Hook, instead of your workflow polling.
More integration guides
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