Looking for a Surepass GST API Alternative

Surepass is a well-known Indian verification API provider, and if you landed here you are probably already using one of these APIs and something made you look around — a renewal, an invoice that grew, a field you keep fetching from somewhere else, a latency spike on a screen a customer stares at. This post is not our opinion of a rival. It is the evaluation you run yourself: eight questions, how to test each one against any provider including us, a blank scorecard, and a migration plan that does not require a leap of faith.

Start with the thing that made you look

Write down, in one sentence, what actually prompted this. It is nearly always one of five things: the bill stopped being forecastable, a field you need is missing or costs a second call, p95 latency broke a user-facing screen, a support ticket went unanswered during an incident, or a renewal date arrived and somebody asked whether this was still the right choice.

That sentence is your pass mark. If you skip it, you will end up comparing feature lists, and feature lists are the least predictive thing on a vendor page. A provider that fixes your specific problem and scores mediocre elsewhere is the right switch; a provider that scores well everywhere except your specific problem is a lateral move that costs you a week.

Everything below is framed as something you ask or measure, not something we assert. We have not audited any competitor's live service, so we do not describe one. If you want the wider market picture first — the categories of provider, what a GSP is and is not, and the criteria that separate them — read how to choose a GST verification API provider, which is the fuller comparison this post sits alongside.

Questions one to three: what a call really costs

1. What does one call cost, and what is the effective cost per useful verification? The headline rate is the beginning of the calculation, not the end. Take everything that will leave your bank account in a year — per-call spend, monthly minimums you will not consume, credits that expire unused — and divide it by the number of calls that returned an answer you could act on. Calls that failed format validation, duplicate lookups and partial records you had to supplement all come out of the denominator.

How to test it. Pull last quarter's real call volume from your logs, including the failures, and run it through each provider's published or quoted rate card. Do not use their example volume. The method is worked through in full in GST API cost per verification, and the traps that inflate the numerator are catalogued in the hidden costs of a cheap GST API.

2. Is filing history returned in the same call as registration details? This is the question that most often doubles a price quietly. If your workflow needs GSTR-1 and GSTR-3B filing periods alongside legal name and status — and most vendor-onboarding and input-tax-credit workflows do — then an API that returns registration details alone is charging you twice for one decision.

How to test it. Send one request for a GSTIN you know files regularly and read the raw response. Count the calls needed to populate every field your database actually stores.

3. Is the pricing published, or only available after a sales call? Published pricing is not a moral virtue, but it is an operational one: you can forecast, you can compare without booking calendar time, and the number does not depend on how well you negotiate. Unpublished pricing is a cost you pay in weeks.

How to test it. Try to get from a cold start to a working API key without speaking to anyone. If you cannot, ask for a written per-verification rate at your forecast annual volume, with the minimum commitment and the credit expiry stated in the same email.

Questions four to eight: the engineering ones

4. Where does the data come from, and how fresh is it? Ask how long a taxpayer record is cached and what invalidates it. Then verify the answer instead of trusting it.

How to test it. Pick a GSTIN whose status you know changed recently — a supplier you know was cancelled or suspended, or one you watched migrate — and query it. A stale "Active" on a cancelled registration is the single most expensive wrong answer this category of API can give you. The sourcing question is unpacked in where GST API data comes from.

5. What is the p95 latency at your real concurrency? A marketing number measured with one request at a time in an empty hour tells you nothing about a batch run at 4pm.

How to test it. Fire your actual concurrency — if your reconciliation job runs 20 requests in parallel, run 20 — for ten minutes, and record p50, p95 and p99 separately. Judge the p95, because that is the one your users feel. Benchmarks and a method are in GST API uptime and latency benchmarks.

6. Is there a published uptime SLA and a status page? An SLA with a number and a remedy is a commitment. "High availability" is a mood. A public status page with incident history tells you how a provider behaves on a bad day, which is the only day that matters.

How to test it. Find the status page without asking. Read the last six months of incidents. If there is no history, ask what the longest outage of the past year was and how customers were told.

7. What does the error taxonomy look like? You need to distinguish, from the response alone and without a human reading it, between "this GSTIN does not exist", "this GSTIN is malformed", "you are rate limited", and "the upstream source is down". Those four need four different behaviours in your code: reject the vendor, fix the input, back off, retry later.

How to test it. Deliberately send a malformed GSTIN, a well-formed but unregistered one, and a burst that exceeds the documented rate limit. Then check your balance: find out which of those was billed. Being charged for a provider's own 5xx is a real cost with a real rate. See the GST API error codes guide.

8. What does bulk actually look like? There is a large difference between a queued batch endpoint that accepts a file of GSTINs and returns a job you poll, and a documentation page that suggests you write a loop. The loop is yours to operate: retries, backoff, partial failure, resumption.

How to test it. Submit 5,000 GSTINs the way you would in production and see what you had to build. The patterns are in the bulk GSTIN verification guide.

A scorecard you fill in yourself

Print this, put your current provider in column A and the candidate in column B, and fill it in from tests rather than from vendor pages. Score each row 0 to 3. The blank cells are the point of the table.

The parallel run that settles it

Before you change production, run both providers against the same 200 GSTINs from your own data and diff the responses field by field. Choose the sample deliberately: include cancelled and suspended registrations, a few composition dealers, some recently amended records, and a handful you know are invalid. A sample of clean, active GSTINs makes every provider look identical.

import fs from 'node:fs';

const gstins = fs.readFileSync('sample-200.txt', 'utf8').trim().split('\n');
const fields = ['legalName', 'tradeName', 'status', 'registrationDate', 'taxpayerType', 'lastFiledPeriod'];

const fetchFrom = async (provider, gstin) => {
  const started = performance.now();
  const res = await fetch(provider.url(gstin), { headers: provider.headers });
  const body = res.ok ? provider.normalise(await res.json()) : null;
  return { ok: res.ok, status: res.status, body, ms: performance.now() - started };
};

const report = [];

for (const gstin of gstins) {
  const [a, b] = await Promise.all([fetchFrom(current, gstin), fetchFrom(candidate, gstin)]);
  const differences = fields.filter((f) => (a.body?.[f] ?? null) !== (b.body?.[f] ?? null));

  if (differences.length || a.ok !== b.ok) {
    report.push({ gstin, differences, aStatus: a.status, bStatus: b.status });
  }
  report.push({ gstin, aMs: Math.round(a.ms), bMs: Math.round(b.ms) });
}

fs.writeFileSync('diff-report.json', JSON.stringify(report, null, 2));

Read the report for three things in order. Disagreements on status come first: check those GSTINs on the government portal the same day and record which provider matched. Disagreements on filing history come second, because a missing or lagging period silently changes a supplier risk score. Field coverage comes third — note every field one returns and the other does not, and decide whether you actually store it.

The loop above already records per-call timings, so sort them and read p95 off the same run that produced your correctness data — one test, two answers, both measured from your own infrastructure under identical network conditions rather than from a vendor's datacentre.

Cutting over without a bad fortnight

The code change is usually a day. The confidence is the rest. A migration that has never gone badly looks like this:

1. Normalise first. If you store raw vendor JSON, add a mapping layer to your own field names before you migrate rather than during it. Every future switch then costs an adapter, not a schema change.
2. Parallel run for a week. Same 200 GSTINs, daily, responses stored. Watch the disagreement rate on status and filing history settle or grow.
3. Cut over behind a feature flag, percentage-based if you can. Start at 5%, sit there for a day, then move.
4. Keep the old key alive and funded for a fortnight. A rollback that needs a purchase order is not a rollback.
5. Alert on the disagreement rate, not just on errors. The failure mode you care about is a confident wrong answer, and it returns HTTP 200.
6. Cancel deliberately. Note the notice period, export anything you need, and check whether unused balance is refundable before the renewal date, not after.

The same sequence works whichever direction you are moving, including away from us. If you are weighing a different incumbent, the sister post on evaluating a Karza alternative uses the identical checklist.

Where we fit, and how to check us

We build one of these APIs, so treat this as a disclosed interest and run the eight questions against us exactly as you would against anyone else. Our answers, in the same order:

• Price. ₹0.50 per verification pay-as-you-go, ₹0.40 once a single credit purchase crosses 2,500 credits. No subscription, no minimum spend, no contract. Purchased credits do not expire, so the expiry term in the cost formula is zero. Published on the pricing page, not behind a call.
• Scope per call. Registration details and GSTR filing history come back in a single response, so the denominator in your cost formula is not halved.
• Freshness. Test it with a GSTIN you know changed recently. That is the only evidence worth having, from us or anyone.
• Latency. p95 under 350ms. Measure it yourself with the loop above at your own concurrency.
• Uptime. A published SLA with a stated remedy, not a number in a footer.
• Errors. Documented codes that separate a non-existent GSTIN from a malformed one from an upstream failure, none of which are guesswork on your side.
• Bulk. A queued endpoint, POST /api/bulk/jobs, accepting up to 10,000 GSTINs per job, so you are not writing the loop.
• Trying it. 20 free credits when you verify your email, expiring 30 days after issue, plus five free lookups a day on the public search tool with no signup at all. You can create a key and run the checklist above without speaking to us.

Where we are not the answer: if your annual volume is in the millions, a negotiated enterprise contract elsewhere may beat ₹0.40 on unit price, and if you need filing, e-way bills or e-invoicing rather than verification, you need a GSP and not us, and the checklist above will tell you so quickly.

Frequently asked questions