Google Sheets Add-on Support

Installing

1. Open any Google Sheet you have edit access to.
2. Choose Extensions, then Add-ons, then Get add-ons.
3. Search for GSTIN Verifier and click Install. Google will list the permissions it asks for; all three are non-sensitive scopes and are explained on the add-on overview page.
4. Reload the spreadsheet. Extensions → GSTIN Verifier → Open sidebar should now be available.

Installation covers only your own account by default. A Workspace administrator can instead install it for a whole domain or organisational unit from the Marketplace listing, in which case no one else needs to install anything themselves.

Getting an API key

The offline formulas and the Validate button need no key at all. The Verify button does, because it queries the government register on your behalf.

1. Create a free account. New accounts start with 20 credits, which is 20 successful lookups.
2. In your dashboard, open API keys and create one. Copy it.
3. In the spreadsheet sidebar, paste it into the API key field and click Save key.

The same key works for the REST API, and both draw from one credit balance. Pricing covers what credits cost beyond the free allowance.

Messages you might see

Each of these is a message the add-on itself produces. Search this page for the wording on your screen.

gstinapi.com rejected the API key

Why: The key stored in the sidebar is wrong, was regenerated, or was deactivated in your dashboard.

Fix: Open the sidebar, choose Remove this key, then paste the current key from your dashboard. Keys are per account, not per spreadsheet — one key works everywhere.

Your credit balance ran out partway through this run

Why: The run consumed the last of your credits. It stops at that point rather than retrying the same failure for every remaining row.

Fix: Everything written before the stop is correct. Top up, then select just the rows still marked as not looked up and run Verify again.

The columns to the right of the selection are not empty

Why: The add-on writes its results immediately to the right of your selection, and it will not silently destroy data that is already there.

Fix: Either insert blank columns to the right of your GSTIN column, or tick the overwrite option in the sidebar if those columns are safe to replace.

That selection is too many rows

Why: Google stops any add-on server call at six minutes, so a run is capped at 500 rows.

Fix: Verify the column in blocks of 500 rows or fewer. Results are written as each block finishes, so nothing is lost between runs.

Select a single column

Why: The selection spans more than one column, so the add-on cannot tell which one holds the GST numbers.

Fix: Click the column letter, or drag down a single column of cells, then re-open the sidebar or click Re-read selection.

Not looked up — the number is not well-formed

Why: This is working as intended, not an error. The row failed the offline format or check-digit test, so sending it would have spent a credit to be told what the add-on already knew.

Fix: Read the Format check column next to it — it names the exact problem, such as a wrong length or a mistyped check digit.

A formula shows #NAME? or Unknown function

Why: The add-on is not installed on this spreadsheet, or the sheet was opened before installation finished.

Fix: Reload the spreadsheet. If the Extensions menu has no GSTIN Verifier entry, install the add-on again from the Marketplace.

Loading… stays on screen in a cell

Why: Google recalculates custom functions in batches and shows this while a large range is being evaluated.

Fix: Wait a few seconds. If a very large range never settles, split it into several formulas over smaller ranges.

Contacting us

Email contact@gstinapi.com with the message you saw, one GSTIN that reproduces the problem, and whether you were using a formula or the sidebar. Please do not send us the whole spreadsheet — we do not need it, and we would rather not hold your data. General questions that are not add-on specific are answered on the contact page and in the site FAQ.

Common questions

In the spreadsheet, open Extensions, then Add-ons, then Manage add-ons, find GSTIN Verifier and choose Uninstall. To revoke the OAuth grant separately, visit your Google account permissions page at myaccount.google.com/permissions and remove GSTIN Verifier. Uninstalling deletes the API key the add-on stored against your Google account. Any results already written into your spreadsheet stay there — they are ordinary cell values.

In Google Apps Script user properties, which are scoped to your Google account and to this add-on. It is not written into the spreadsheet, is not visible to anyone you share the file with, and is not stored on our servers beyond the normal record of which key made which request. If you share the spreadsheet, collaborators will need to enter their own key to run the Verify pass.

Yes. Each person authorises the add-on separately and stores their own API key, so credits are drawn from whichever account ran the verification. The offline formulas work for everyone with access to the file, including people who have never entered a key.

The number is well-formed but the government register has no active or historical registration matching it. That usually means a transposed character that still happens to produce a valid checksum, or a number that was never issued. No credit is charged for that outcome.

Within one business day, Monday to Friday, India Standard Time. Include the spreadsheet behaviour you saw, the exact message from the sidebar, and one example GSTIN that reproduces it — that is almost always enough to answer in the first reply.

Add-on support