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API · /gst-api

GST API

healthy 3,943 Subscribers

Validate and decode Indian GSTINs (the 15-character Goods & Services Tax Identification Number) instantly and entirely offline. The validate endpoint checks the structure and recomputes the official GSTIN check digit — the base-36 weighted algorithm the GSTN itself uses — and confirms the embedded state code is real, returning a clear valid/invalid verdict with the specific reasons a number fails. The decode endpoint breaks a GSTIN into its parts: the GST state/UT code and its name, the embedded 10-character PAN, the PAN holder type (company, individual/proprietor, firm/LLP, HUF, trust, government and more, read from the PAN's 4th letter), the entity registration number, the default 'Z' slot and the check digit. A states endpoint returns the full GST state-code reference for building dropdowns and lookups. Everything is pure computation — no network call, no key, no cache — so it is fast and private, ideal for checkout and onboarding forms, invoicing and e-invoice/e-way-bill pipelines, vendor master data cleansing and bulk validation. A structural GSTIN validator and decoder — distinct from EU VAT-number validation (vat), IBAN bank-account validation (iban) and card-number checks (creditcard). Note: this verifies the number's structure and check digit, not whether it is actively registered in the GSTN portal. No upstream key, no cache.

#gst #gstin #india #tax #validation #developer-tools
api.oanor.com/gst-api
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Machine-readable spec so AI agents can integrate this API.

/api/gst-api/openapi.json
/api/gst-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
78 ms
Server probes · 24h
Subscribers
3,943
active
Total calls
4
last 7 days
status Full status page → · 8 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 2,095 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 2,095 calls/month
  • 2 req/sec
  • Validate + decode
  • No credit card
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Starter

€6.18 /month

  • 40,300 calls / month
  • 8 requests / second
  • Hard cap (429 above quota, no overage)
  • 40.3k calls/month
  • 8 req/sec
  • Check digit + PAN/state decode
  • Email support
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Pro

€20.35 /month

  • 213,000 calls / month
  • 20 requests / second
  • Hard cap (429 above quota, no overage)
  • 213k calls/month
  • 20 req/sec
  • Bulk validation pipelines
  • Priority support
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Mega

€52.70 /month

  • 810,000 calls / month
  • 50 requests / second
  • Hard cap (429 above quota, no overage)
  • 810k calls/month
  • 50 req/sec
  • Invoicing-platform scale
  • Dedicated SLA
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Related APIs

Other APIs with overlapping tags.

VAT & Sales Tax API

VAT, GST and sales-tax rates for 128 countries — plus US state and Canadian province sub-rates — with a built-in tax calculator. Get the standard rate for any country (e.g. DE → 19%), compute the tax and gross total on a net amount (e.g. €100 in Germany → €19 tax, €119 total), apply a US state or Canadian province rate, or list every country. Ideal for e-commerce checkouts, invoicing, SaaS billing and pricing tools. (Standard rates, not tax advice.)

api.oanor.com/vat-api

JSON Schema API

Validate JSON against JSON Schema, server-side. Check any data against a schema (Draft-07 or 2020-12) and get a clear pass/fail plus a detailed list of every error with its instance path, failing keyword and message; verify that a schema itself is well-formed; or infer a starter JSON Schema automatically from a sample document, complete with detected formats like email, URI and date. Built on the battle-tested Ajv engine with full format validation. Every endpoint accepts GET (JSON-encoded parameters) or a JSON POST body and runs entirely locally with no third-party upstream, so responses are instant and the service is always available. Ideal for API request/response validation, form and data-entry checks, ETL and data-quality pipelines, no-code platforms and contract testing.

api.oanor.com/jsonschema-api

Credit Card API

A fast, fully-local payment-card toolkit: validate card numbers with the Luhn (mod-10) checksum, detect the brand by IIN/prefix (Visa, Mastercard including the 2-series, American Express, Discover, Diners, JCB, UnionPay, Maestro), format and mask numbers with brand-correct grouping, list supported brands with their valid lengths and CVV length, and generate synthetic Luhn-valid TEST card numbers for QA. Pure server-side compute, no third-party upstream, and inputs are never logged. It is algorithmic only (no real issuer/bank BIN-database lookup). Ideal for checkout forms, payment flows, fraud pre-checks and test fixtures.

api.oanor.com/creditcard-api

IBAN Validation API

Validate IBANs with the ISO 7064 mod-97 checksum and per-country length and structure checks, and resolve the BIC and bank details for supported countries. A local parse endpoint works for every IBAN country offline; the validate endpoint adds bank-code verification and BIC. Ideal for payments, billing, onboarding and KYC.

api.oanor.com/iban-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for GST API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call GST API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for GST API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does GST API cost?
GST API has a free tier with 100 calls / month. Paid plans start at €6.18 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is GST API GDPR-compliant?
All requests to GST API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/gst-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/gst-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/gst-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/gst-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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